[kj] mark of the beast closer than expected

[jpwhkj at aol.com]

"most of the victims had illnesses anyway"

True, but what were those illnesses (or "underlying health problems" as the papers tend to say)?  Apparently this included someone who was obese - hardly an imminent risk of death.  (Let's face it, most of us have underlying health problems of some description.)  Source for that:

http://www.guardian.co.uk/world/2009/jul/14/swine-flu-virus-uk

I'm naturally suspicious of media frenzies (for example, the current death rate in the UK is tiny, suggesting that there's not much to worry about) but then I'm also naturally suspicious of government ministers saying "don't panic"...

Jamie


-----Original Message-----
From: Stephen Lawrence <stephen.l at live.com>
To: gathering at misera.net <gathering at misera.net>
Sent: Tue, 14 Jul 2009 18:34
Subject: Re: [kj] mark of the beast closer than expected


folk 
i'm sure you are aware of the avian flu scandal of 76 
quite a few people died as a result of that vaccine 
seems like they wanna have another go 
all these swine flu deaths have been blown out of proportion 
most of the victims had illnesses anyway 
health is big business 
as you said interesting how tamilflu is out of the equation 
 
From: folk.devil at hotmail.com
To: gathering at misera.net
Date: Tue, 14 Jul 2009 10:26:53 -0700
Subject: Re: [kj] mark of the beast closer than expected


seems that link is 'limited'...

 

Influenza Antiviral Resistance: Issues for Consideration December 19, 2008 Background 



• CDC recommends annual influenza vaccination=2
0as the first and most important step in preventing the flu. 




• Antiviral medications with activity against influenza viruses are a second line of defense against influenza. 






• Antiviral medications are important to consider especially for treatment of patients with severe influenza or patients at higher risk for influenza-related complications. 






• There are four antiviral medications approved for use in the United States: oseltamivir, zanamivir, amantadine and rimantadine. 







o Oseltamivir and zanamivir have activity against influenza A and B viruses. 





o Amantadine and rimantadine have activity against influenza A viruses, but not against influenza B viruses. 




• Influenza viruses can develop resistance to antiviral medications. 






• Since 2006, CDC has recommended the use of oseltamivir and zanamivir against seasonal influenza because of a high resistance to amantadine and rimantadine among influenza A (H3N2) viruses. 






• In the last two years, CDC has enhanced surveillance efforts for the detection of viruses resistant to oseltamivir (Tamiflu®) and zanamivir (Relenza®). 




• These enhanced efforts have provided CDC with the capability to detect resistant strains more quickly, and enabled CDC to monitor for changing trends over time. 






• During the 2007-08 influenza season, a small increase in the number of influenza viruses resistant to oseltamivir was observed. 







• CDC’s influenza season summary for 2007-2008 reported that 10.9% of tested influenza A (H1N1) viruses were resistant to oseltamivir. 






• Last season, CDC tested 1,769 viruses for antiviral resistance. 






• During the 2007-08 influenza season in the Northern Hemisphere, oseltamivir resistance of H1N1 viruses varied in different countries: from 0% to 70% in some European countries. 






• During the 2008 Southern Hemisphere season, oseltamivir resistance of H1N1 viruses continued to be reported, with some Southern Hemisphere countries reporting that a majority of tested A (H1N1) viruses were resistant to oseltamivir. 






Amantadine and rimantadine have activity against influenza A viruses, but not against influenza B viruses. 




• Influenza viruses can develop resistance to antiviral medications. 






• Since 2006, CDC has recommended the use of oseltamivir and zanamivir against seasonal influenza because of a high resistance to amantadine and rimantadine among influenza A (H3N2) viruses. 






• In the last two years, CDC has enhanced surveillance efforts for the detection of viruses resistant to oseltamivir (Tamiflu®) and zanamivir (Relenza®). 




• These enhanced efforts have provided CDC with the capability to detect resistant strains more quickly, and enabled CDC to monitor for changing trends over time. 






• During the 2007-08 influenza season, a small increase in t
he number of influenza viruses resistant to oseltamivir was observed. 






• CDC’s influenza season summary for 2007-2008 reported that 10.9% of tested influenza A (H1N1) viruses were resistant to oseltamivir. 






• Last season, CDC tested 1,769 viruses for antiviral resistance. 






• During the 2007-08 influenza season in the Northern Hemisphere, oseltamivir resistance of H1N1 viruses varied in different countries: from 0% to 70% in some European countries. 






• During the 2008 Southern Hemisphere season, oseltamivir resistance of H1N1 viruses continued to be reported, with some Southern Hemisphere countries reporting that a majority of tested A (H1N1) viruses were resistant to oseltamivir. 








Oseltamivir and zanamivir have activity against influenza A and B viruses. 





o Amantadine and rimantadine have activity against influenza A viruses, but not against influenza B viruses. 




• Influenza viruses can develop resistance to antiviral medications. 






• Since 2006, CDC has recommended the use of oseltamivir and zanamivir against seasonal influenza because of a high resistance to amantadine and rimantadine among influenza A (H3N2) viruses. 






• In the last two years, CDC has enhanced surveillance efforts for the detection of viruses resistant to oseltamivir (Tamiflu®) and zanamivir (Relenza®). 




• These enhanced efforts have provided CDC with the capability to detect resist
ant strains more quickly, and enabled CDC to monitor for changing trends over time. 






• During the 2007-08 influenza season, a small increase in the number of influenza viruses resistant to oseltamivir was observed. 






• CDC’s influenza season summary for 2007-2008 reported that 10.9% of tested influenza A (H1N1) viruses were resistant to oseltamivir. 






• Last season, CDC tested 1,769 viruses for antiviral resistance. 






• During the 2007-08 influenza season in the Northern Hemisphere, oseltamivir resistance of H1N1 viruses varied in different countries: from 0% to 70% in some European countries. 






• During the 2008 Southern Hemisphere season, oseltamivir resistance of H1N1 viruses continued to be reported, with some Southern Hemisphere countries reporting that a majority of tested A (H1N1) viruses were resistant to oseltamivir. 






Amantadine and rimantadine have activity against influenza A viruses, but not against influenza B viruses. 




• Influenza viruses can develop resistance to antiviral medications. 






• Since 2006, CDC has recommended the use of oseltamivir and zanamivir against seasonal influenza because of a high resistance to amantadine and rimantadine among influenza A (H3N2) viruses. 






• In the last two years, CDC has enhanced surveillance efforts for the detection of viruses resistant to oseltamivir (Tamiflu®) and zanamivir (Relenza®). 




• The
se enhanced efforts have provided CDC with the capability to detect resistant strains more quickly, and enabled CDC to monitor for changing trends over time. 






• During the 2007-08 influenza season, a small increase in the number of influenza viruses resistant to oseltamivir was observed. 






• CDC’s influenza season summary for 2007-2008 reported that 10.9% of tested influenza A (H1N1) viruses were resistant to oseltamivir. 






• Last season, CDC tested 1,769 viruses for antiviral resistance. 






• During the 2007-08 influenza season in the Northern Hemisphere, oseltamivir resistance of H1N1 viruses varied in different countries: from 0% to 70% in some European countries. 






• During the 2008 Southern Hemisphere season, oseltamivir resistance of H1N1 viruses continued to be reported, with some Southern Hemisphere countries reporting that a majority of tested A (H1N1) viruses were resistant to oseltamivir. 










CDC recommends annual influenza vaccination as the first and most important step in preventing the flu. 




• Antiviral medications with activity against influenza viruses are a second line of defense against influenza. 






• Antiviral medications are important to consider especially for treatment of patients with severe influenza or patients at higher risk for influenza-related complications. 






• There are four antiviral medications approved for use in the United States: os
eltamivir, zanamivir, amantadine and rimantadine. 







o Oseltamivir and zanamivir have activity against influenza A and B viruses. 





o Amantadine and rimantadine have activity against influenza A viruses, but not against influenza B viruses. 




• Influenza viruses can develop resistance to antiviral medications. 






• Since 2006, CDC has recommended the use of oseltamivir and zanamivir against seasonal influenza because of a high resistance to amantadine and rimantadine among influenza A (H3N2) viruses. 






• In the last two years, CDC has enhanced surveillance efforts for the detection of viruses resistant to oseltamivir (Tamiflu®) and zanamivir (Relenza®). 




• These enhanced efforts have provided CDC with the capability to detect resistant strains more quickly, and enabled CDC to monitor for changing trends over time. 






• During the 2007-08 influenza season, a small increase in the number of influenza viruses resistant to oseltamivir was observed. 






• CDC’s influenza season summary for 2007-2008 reported that 10.9% of tested influenza A (H1N1) viruses were resistant to oseltamivir. 






• Last season, CDC tested 1,769 viruses for antiviral resistance. 






• During the 2007-08 influenza season in the Northern Hemisphere, oseltamivir resistance of H1N1 viruses varied in different countries: from 0% to 70% in some European countries. 






• During the 20
08 Southern Hemisphere season, oseltamivir resistance of H1N1 viruses continued to be reported, with some Southern Hemisphere countries reporting that a majority of tested A (H1N1) viruses were resistant to oseltamivir. 






Amantadine and rimantadine have activity against influenza A viruses, but not against influenza B viruses. 




• Influenza viruses can develop resistance to antiviral medications. 






• Since 2006, CDC has recommended the use of oseltamivir and zanamivir against seasonal influenza because of a high resistance to amantadine and rimantadine among influenza A (H3N2) viruses. 






• In the last two years, CDC has enhanced surveillance efforts for the detection of viruses resistant to oseltamivir (Tamiflu®) and zanamivir (Relenza®). 




• These enhanced efforts have provided CDC with the capability to detect resistant strains more quickly, and enabled CDC to monitor for changing trends over time. 






• During the 2007-08 influenza season, a small increase in the number of influenza viruses resistant to oseltamivir was observed. 






• CDC’s influenza season summary for 2007-2008 reported that 10.9% of tested influenza A (H1N1) viruses were resistant to oseltamivir. 






• Last season, CDC tested 1,769 viruses for antiviral resistance. 






• During the 2007-08 influenza season in the Northern Hemisphere, oseltamivir resistance of H1N1 viruses varied in different countries: from 0% t
o 70% in some European countries. 






• During the 2008 Southern Hemisphere season, oseltamivir resistance of H1N1 viruses continued to be reported, with some Southern Hemisphere countries reporting that a majority of tested A (H1N1) viruses were resistant to oseltamivir. 








Oseltamivir and zanamivir have activity against influenza A and B viruses. 





o Amantadine and rimantadine have activity against influenza A viruses, but not against influenza B viruses. 




• Influenza viruses can develop resistance to antiviral medications. 






• Since 2006, CDC has recommended the use of oseltamivir and zanamivir against seasonal influenza because of a high resistance to amantadine and rimantadine among influenza A (H3N2) viruses. 






• In the last two years, CDC has enhanced surveillance efforts for the detection of viruses resistant to oseltamivir (Tamiflu®) and zanamivir (Relenza®). 




• These enhanced efforts have provided CDC with the capability to detect resistant strains more quickly, and enabled CDC to monitor for changing trends over time. 






• During the 2007-08 influenza season, a small increase in the number of influenza viruses resistant to oseltamivir was observed. 






• CDC’s influenza season summary for 2007-2008 reported that 10.9% of tested influenza A (H1N1) viruses were resistant to oseltamivir. 






• Last season, CDC tested 1,769 viruses for antiviral resistanc
e. 






• During the 2007-08 influenza season in the Northern Hemisphere, oseltamivir resistance of H1N1 viruses varied in different countries: from 0% to 70% in some European countries. 






• During the 2008 Southern Hemisphere season, oseltamivir resistance of H1N1 viruses continued to be reported, with some Southern Hemisphere countries reporting that a majority of tested A (H1N1) viruses were resistant to oseltamivir. 






Amantadine and rimantadine have activity against influenza A viruses, but not against influenza B viruses. 




• Influenza viruses can develop resistance to antiviral medications. 






• Since 2006, CDC has recommended the use of oseltamivir and zanamivir against seasonal influenza because of a high resistance to amantadine and rimantadine among influenza A (H3N2) viruses. 






• In the last two years, CDC has enhanced surveillance efforts for the detection of viruses resistant to oseltamivir (Tamiflu®) and zanamivir (Relenza®). 




• These enhanced efforts have provided CDC with the capability to detect resistant strains more quickly, and enabled CDC to monitor for changing trends over time. 






• During the 2007-08 influenza season, a small increase in the number of influenza viruses resistant to oseltamivir was observed. 






• CDC’s influenza season summary for 2007-2008 reported that 10.9% of tested influenza A (H1N1) viruses were resistant to oseltamivir. 



=0
A

• Last season, CDC tested 1,769 viruses for antiviral resistance. 






• During the 2007-08 influenza season in the Northern Hemisphere, oseltamivir resistance of H1N1 viruses varied in different countries: from 0% to 70% in some European countries. 






• During the 2008 Southern Hemisphere season, oseltamivir resistance of H1N1 viruses continued to be reported, with some Southern Hemisphere countries reporting that a majority of tested A (H1N1) viruses were resistant to oseltamivir. 















• CDC recommends annual influenza vaccination as the first and most important step in preventing the flu. 




• Antiviral medications with activity against influenza viruses are a second line of defense against influenza. 






• Antiviral medications are important to consider especially for treatment of patients with severe influenza or patients at higher risk for influenza-related complications. 






• There are four antiviral medications approved for use in the United States: oseltamivir, zanamivir, amantadine and rimantadine. 







o Oseltamivir and zanamivir have activity against influenza A and B viruses. 





o Amantadine and rimantadine have activity against influenza A viruses, but not against influenza B viruses. 




• Influenza viruses can develop resistance to antiviral medications. 






• Since 2006, CDC has recommended the use of oseltamivir and zanamivir against seasonal influen
za because of a high resistance to amantadine and rimantadine among influenza A (H3N2) viruses. 






• In the last two years, CDC has enhanced surveillance efforts for the detection of viruses resistant to oseltamivir (Tamiflu®) and zanamivir (Relenza®). 




• These enhanced efforts have provided CDC with the capability to detect resistant strains more quickly, and enabled CDC to monitor for changing trends over time. 






• During the 2007-08 influenza season, a small increase in the number of influenza viruses resistant to oseltamivir was observed. 






• CDC’s influenza season summary for 2007-2008 reported that 10.9% of tested influenza A (H1N1) viruses were resistant to oseltamivir. 






• Last season, CDC tested 1,769 viruses for antiviral resistance. 






• During the 2007-08 influenza season in the Northern Hemisphere, oseltamivir resistance of H1N1 viruses varied in different countries: from 0% to 70% in some European countries. 






• During the 2008 Southern Hemisphere season, oseltamivir resistance of H1N1 viruses continued to be reported, with some Southern Hemisphere countries reporting that a majority of tested A (H1N1) viruses were resistant to oseltamivir. 






Amantadine and rimantadine have activity against influenza A viruses, but not against influenza B viruses. 




• Influenza viruses can develop resistance to antiviral medications. 






• Since 2006, CDC h
as recommended the use of oseltamivir and zanamivir against seasonal influenza because of a high resistance to amantadine and rimantadine among influenza A (H3N2) viruses. 






• In the last two years, CDC has enhanced surveillance efforts for the detection of viruses resistant to oseltamivir (Tamiflu®) and zanamivir (Relenza®). 




• These enhanced efforts have provided CDC with the capability to detect resistant strains more quickly, and enabled CDC to monitor for changing trends over time. 






• During the 2007-08 influenza season, a small increase in the number of influenza viruses resistant to oseltamivir was observed. 






• CDC’s influenza season summary for 2007-2008 reported that 10.9% of tested influenza A (H1N1) viruses were resistant to oseltamivir. 






• Last season, CDC tested 1,769 viruses for antiviral resistance. 






• During the 2007-08 influenza season in the Northern Hemisphere, oseltamivir resistance of H1N1 viruses varied in different countries: from 0% to 70% in some European countries. 






• During the 2008 Southern Hemisphere season, oseltamivir resistance of H1N1 viruses continued to be reported, with some Southern Hemisphere countries reporting that a majority of tested A (H1N1) viruses were resistant to oseltamivir. 








Oseltamivir and zanamivir have activity against influenza A and B viruses. 





o Amantadine and rimantadine have activity against influenza A virus
es, but not against influenza B viruses. 




• Influenza viruses can develop resistance to antiviral medications. 






• Since 2006, CDC has recommended the use of oseltamivir and zanamivir against seasonal influenza because of a high resistance to amantadine and rimantadine among influenza A (H3N2) viruses. 






• In the last two years, CDC has enhanced surveillance efforts for the detection of viruses resistant to oseltamivir (Tamiflu®) and zanamivir (Relenza®). 




• These enhanced efforts have provided CDC with the capability to detect resistant strains more quickly, and enabled CDC to monitor for changing trends over time. 






• During the 2007-08 influenza season, a small increase in the number of influenza viruses resistant to oseltamivir was observed. 






• CDC’s influenza season summary for 2007-2008 reported that 10.9% of tested influenza A (H1N1) viruses were resistant to oseltamivir. 






• Last season, CDC tested 1,769 viruses for antiviral resistance. 






• During the 2007-08 influenza season in the Northern Hemisphere, oseltamivir resistance of H1N1 viruses varied in different countries: from 0% to 70% in some European countries. 






• During the 2008 Southern Hemisphere season, oseltamivir resistance of H1N1 viruses continued to be reported, with some Southern Hemisphere countries reporting that a majority of tested A (H1N1) viruses were resistant to oseltamivir. 

0A



Amantadine and rimantadine have activity against influenza A viruses, but not against influenza B viruses. 




• Influenza viruses can develop resistance to antiviral medications. 






• Since 2006, CDC has recommended the use of oseltamivir and zanamivir against seasonal influenza because of a high resistance to amantadine and rimantadine among influenza A (H3N2) viruses. 






• In the last two years, CDC has enhanced surveillance efforts for the detection of viruses resistant to oseltamivir (Tamiflu®) and zanamivir (Relenza®). 




• These enhanced efforts have provided CDC with the capability to detect resistant strains more quickly, and enabled CDC to monitor for changing trends over time. 






• During the 2007-08 influenza season, a small increase in the number of influenza viruses resistant to oseltamivir was observed. 






• CDC’s influenza season summary for 2007-2008 reported that 10.9% of tested influenza A (H1N1) viruses were resistant to oseltamivir. 






• Last season, CDC tested 1,769 viruses for antiviral resistance. 






• During the 2007-08 influenza season in the Northern Hemisphere, oseltamivir resistance of H1N1 viruses varied in different countries: from 0% to 70% in some European countries. 






• During the 2008 Southern Hemisphere season, oseltamivir resistance of H1N1 viruses continued to be reported, with some Southern Hemisphere countries reporting that a20majority of tested A (H1N1) viruses were resistant to oseltamivir. 










CDC recommends annual influenza vaccination as the first and most important step in preventing the flu. 




• Antiviral medications with activity against influenza viruses are a second line of defense against influenza. 






• Antiviral medications are important to consider especially for treatment of patients with severe influenza or patients at higher risk for influenza-related complications. 






• There are four antiviral medications approved for use in the United States: oseltamivir, zanamivir, amantadine and rimantadine. 







o Oseltamivir and zanamivir have activity against influenza A and B viruses. 





o Amantadine and rimantadine have activity against influenza A viruses, but not against influenza B viruses. 




• Influenza viruses can develop resistance to antiviral medications. 






• Since 2006, CDC has recommended the use of oseltamivir and zanamivir against seasonal influenza because of a high resistance to amantadine and rimantadine among influenza A (H3N2) viruses. 






• In the last two years, CDC has enhanced surveillance efforts for the detection of viruses resistant to oseltamivir (Tamiflu®) and zanamivir (Relenza®). 




• These enhanced efforts have provided CDC with the capability to detect resistant strains more quickly, and enabled CDC to monitor for changing trends over time. 






•
 During the 2007-08 influenza season, a small increase in the number of influenza viruses resistant to oseltamivir was observed. 






• CDC’s influenza season summary for 2007-2008 reported that 10.9% of tested influenza A (H1N1) viruses were resistant to oseltamivir. 






• Last season, CDC tested 1,769 viruses for antiviral resistance. 






• During the 2007-08 influenza season in the Northern Hemisphere, oseltamivir resistance of H1N1 viruses varied in different countries: from 0% to 70% in some European countries. 






• During the 2008 Southern Hemisphere season, oseltamivir resistance of H1N1 viruses continued to be reported, with some Southern Hemisphere countries reporting that a majority of tested A (H1N1) viruses were resistant to oseltamivir. 






Amantadine and rimantadine have activity against influenza A viruses, but not against influenza B viruses. 




• Influenza viruses can develop resistance to antiviral medications. 






• Since 2006, CDC has recommended the use of oseltamivir and zanamivir against seasonal influenza because of a high resistance to amantadine and rimantadine among influenza A (H3N2) viruses. 






• In the last two years, CDC has enhanced surveillance efforts for the detection of viruses resistant to oseltamivir (Tamiflu®) and zanamivir (Relenza®). 




• These enhanced efforts have provided CDC with the capability to detect resistant strains more quickly, and enable
d CDC to monitor for changing trends over time. 






• During the 2007-08 influenza season, a small increase in the number of influenza viruses resistant to oseltamivir was observed. 






• CDC’s influenza season summary for 2007-2008 reported that 10.9% of tested influenza A (H1N1) viruses were resistant to oseltamivir. 






• Last season, CDC tested 1,769 viruses for antiviral resistance. 






• During the 2007-08 influenza season in the Northern Hemisphere, oseltamivir resistance of H1N1 viruses varied in different countries: from 0% to 70% in some European countries. 






• During the 2008 Southern Hemisphere season, oseltamivir resistance of H1N1 viruses continued to be reported, with some Southern Hemisphere countries reporting that a majority of tested A (H1N1) viruses were resistant to oseltamivir. 








Oseltamivir and zanamivir have activity against influenza A and B viruses. 





o Amantadine and rimantadine have activity against influenza A viruses, but not against influenza B viruses. 




• Influenza viruses can develop resistance to antiviral medications. 






• Since 2006, CDC has recommended the use of oseltamivir and zanamivir against seasonal influenza because of a high resistance to amantadine and rimantadine among influenza A (H3N2) viruses. 






• In the last two years, CDC has enhanced surveillance efforts for the detection of viruses resistant to oseltamivir (Tamif
lu®) and zanamivir (Relenza®). 




• These enhanced efforts have provided CDC with the capability to detect resistant strains more quickly, and enabled CDC to monitor for changing trends over time. 






• During the 2007-08 influenza season, a small increase in the number of influenza viruses resistant to oseltamivir was observed. 






• CDC’s influenza season summary for 2007-2008 reported that 10.9% of tested influenza A (H1N1) viruses were resistant to oseltamivir. 






• Last season, CDC tested 1,769 viruses for antiviral resistance. 






• During the 2007-08 influenza season in the Northern Hemisphere, oseltamivir resistance of H1N1 viruses varied in different countries: from 0% to 70% in some European countries. 






• During the 2008 Southern Hemisphere season, oseltamivir resistance of H1N1 viruses continued to be reported, with some Southern Hemisphere countries reporting that a majority of tested A (H1N1) viruses were resistant to oseltamivir. 






Amantadine and rimantadine have activity against influenza A viruses, but not against influenza B viruses. 




• Influenza viruses can develop resistance to antiviral medications. 






• Since 2006, CDC has recommended the use of oseltamivir and zanamivir against seasonal influenza because of a high resistance to amantadine and rimantadine among influenza A (H3N2) viruses. 






• In the last two years, CDC has enhanced surve
illance efforts for the detection of viruses resistant to oseltamivir (Tamiflu®) and zanamivir (Relenza®). 




• These enhanced efforts have provided CDC with the capability to detect resistant strains more quickly, and enabled CDC to monitor for changing trends over time. 






• During the 2007-08 influenza season, a small increase in the number of influenza viruses resistant to oseltamivir was observed. 






• CDC’s influenza season summary for 2007-2008 reported that 10.9% of tested influenza A (H1N1) viruses were resistant to oseltamivir. 






• Last season, CDC tested 1,769 viruses for antiviral resistance. 






• During the 2007-08 influenza season in the Northern Hemisphere, oseltamivir resistance of H1N1 viruses varied in different countries: from 0% to 70% in some European countries. 






• During the 2008 Southern Hemisphere season, oseltamivir resistance of H1N1 viruses continued to be reported, with some Southern Hemisphere countries reporting that a majority of tested A (H1N1) viruses were resistant to oseltamivir. 














• Antiviral medications with activity against influenza viruses are a second line of defense against influenza. 






• Antiviral medications are important to consider especially for treatment of patients with severe influenza or patients at higher risk for influenza-related complications. 






• There are four antiviral medications approved for us
e in the United States: oseltamivir, zanamivir, amantadine and rimantadine. 







o Oseltamivir and zanamivir have activity against influenza A and B viruses. 





o Amantadine and rimantadine have activity against influenza A viruses, but not against influenza B viruses. 




• Influenza viruses can develop resistance to antiviral medications. 






• Since 2006, CDC has recommended the use of oseltamivir and zanamivir against seasonal influenza because of a high resistance to amantadine and rimantadine among influenza A (H3N2) viruses. 






• In the last two years, CDC has enhanced surveillance efforts for the detection of viruses resistant to oseltamivir (Tamiflu®) and zanamivir (Relenza®). 




• These enhanced efforts have provided CDC with the capability to detect resistant strains more quickly, and enabled CDC to monitor for changing trends over time. 






• During the 2007-08 influenza season, a small increase in the number of influenza viruses resistant to oseltamivir was observed. 






• CDC’s influenza season summary for 2007-2008 reported that 10.9% of tested influenza A (H1N1) viruses were resistant to oseltamivir. 






• Last season, CDC tested 1,769 viruses for antiviral resistance. 






• During the 2007-08 influenza season in the Northern Hemisphere, oseltamivir resistance of H1N1 viruses varied in different countries: from 0% to 70% in some European countries. 



=0
A

• During the 2008 Southern Hemisphere season, oseltamivir resistance of H1N1 viruses continued to be reported, with some Southern Hemisphere countries reporting that a majority of tested A (H1N1) viruses were resistant to oseltamivir. 






Amantadine and rimantadine have activity against influenza A viruses, but not against influenza B viruses. 




• Influenza viruses can develop resistance to antiviral medications. 






• Since 2006, CDC has recommended the use of oseltamivir and zanamivir against seasonal influenza because of a high resistance to amantadine and rimantadine among influenza A (H3N2) viruses. 






• In the last two years, CDC has enhanced surveillance efforts for the detection of viruses resistant to oseltamivir (Tamiflu®) and zanamivir (Relenza®). 




• These enhanced efforts have provided CDC with the capability to detect resistant strains more quickly, and enabled CDC to monitor for changing trends over time. 






• During the 2007-08 influenza season, a small increase in the number of influenza viruses resistant to oseltamivir was observed. 






• CDC’s influenza season summary for 2007-2008 reported that 10.9% of tested influenza A (H1N1) viruses were resistant to oseltamivir. 






• Last season, CDC tested 1,769 viruses for antiviral resistance. 






• During the 2007-08 influenza season in the Northern Hemisphere, oseltamivir resistance of H1N1 viruses varied in di
fferent countries: from 0% to 70% in some European countries. 






• During the 2008 Southern Hemisphere season, oseltamivir resistance of H1N1 viruses continued to be reported, with some Southern Hemisphere countries reporting that a majority of tested A (H1N1) viruses were resistant to oseltamivir. 








Oseltamivir and zanamivir have activity against influenza A and B viruses. 





o Amantadine and rimantadine have activity against influenza A viruses, but not against influenza B viruses. 




• Influenza viruses can develop resistance to antiviral medications. 






• Since 2006, CDC has recommended the use of oseltamivir and zanamivir against seasonal influenza because of a high resistance to amantadine and rimantadine among influenza A (H3N2) viruses. 






• In the last two years, CDC has enhanced surveillance efforts for the detection of viruses resistant to oseltamivir (Tamiflu®) and zanamivir (Relenza®). 




• These enhanced efforts have provided CDC with the capability to detect resistant strains more quickly, and enabled CDC to monitor for changing trends over time. 






• During the 2007-08 influenza season, a small increase in the number of influenza viruses resistant to oseltamivir was observed. 






• CDC’s influenza season summary for 2007-2008 reported that 10.9% of tested influenza A (H1N1) viruses were resistant to oseltamivir. 






• Last season, CDC tested 1,769 v
iruses for antiviral resistance. 






• During the 2007-08 influenza season in the Northern Hemisphere, oseltamivir resistance of H1N1 viruses varied in different countries: from 0% to 70% in some European countries. 






• During the 2008 Southern Hemisphere season, oseltamivir resistance of H1N1 viruses continued to be reported, with some Southern Hemisphere countries reporting that a majority of tested A (H1N1) viruses were resistant to oseltamivir. 






Amantadine and rimantadine have activity against influenza A viruses, but not against influenza B viruses. 




• Influenza viruses can develop resistance to antiviral medications. 






• Since 2006, CDC has recommended the use of oseltamivir and zanamivir against seasonal influenza because of a high resistance to amantadine and rimantadine among influenza A (H3N2) viruses. 






• In the last two years, CDC has enhanced surveillance efforts for the detection of viruses resistant to oseltamivir (Tamiflu®) and zanamivir (Relenza®). 




• These enhanced efforts have provided CDC with the capability to detect resistant strains more quickly, and enabled CDC to monitor for changing trends over time. 






• During the 2007-08 influenza season, a small increase in the number of influenza viruses resistant to oseltamivir was observed. 






• CDC’s influenza season summary for 2007-2008 reported that 10.9% of tested influenza A (H1N1) viruses were resistant20to oseltamivir. 






• Last season, CDC tested 1,769 viruses for antiviral resistance. 






• During the 2007-08 influenza season in the Northern Hemisphere, oseltamivir resistance of H1N1 viruses varied in different countries: from 0% to 70% in some European countries. 






• During the 2008 Southern Hemisphere season, oseltamivir resistance of H1N1 viruses continued to be reported, with some Southern Hemisphere countries reporting that a majority of tested A (H1N1) viruses were resistant to oseltamivir. 














o Amantadine and rimantadine have activity against influenza A viruses, but not against influenza B viruses. 




• Influenza viruses can develop resistance to antiviral medications. 






• Since 2006, CDC has recommended the use of oseltamivir and zanamivir against seasonal influenza because of a high resistance to amantadine and rimantadine among influenza A (H3N2) viruses. 






• In the last two years, CDC has enhanced surveillance efforts for the detection of viruses resistant to oseltamivir (Tamiflu®) and zanamivir (Relenza®). 




• These enhanced efforts have provided CDC with the capability to detect resistant strains more quickly, and enabled CDC to monitor for changing trends over time. 






• During the 2007-08 influenza season, a small increase in the number of influenza viruses resistant to oseltamivir was observed. 






• CDC’s influenza seaso
n summary for 2007-2008 reported that 10.9% of tested influenza A (H1N1) viruses were resistant to oseltamivir. 






• Last season, CDC tested 1,769 viruses for antiviral resistance. 






• During the 2007-08 influenza season in the Northern Hemisphere, oseltamivir resistance of H1N1 viruses varied in different countries: from 0% to 70% in some European countries. 






• During the 2008 Southern Hemisphere season, oseltamivir resistance of H1N1 viruses continued to be reported, with some Southern Hemisphere countries reporting that a majority of tested A (H1N1) viruses were resistant to oseltamivir. 






Amantadine and rimantadine have activity against influenza A viruses, but not against influenza B viruses. 




• Influenza viruses can develop resistance to antiviral medications. 






• Since 2006, CDC has recommended the use of oseltamivir and zanamivir against seasonal influenza because of a high resistance to amantadine and rimantadine among influenza A (H3N2) viruses. 






• In the last two years, CDC has enhanced surveillance efforts for the detection of viruses resistant to oseltamivir (Tamiflu®) and zanamivir (Relenza®). 




• These enhanced efforts have provided CDC with the capability to detect resistant strains more quickly, and enabled CDC to monitor for changing trends over time. 






• During the 2007-08 influenza season, a small increase in the number of influenza viruses resistant to os
eltamivir was observed. 






• CDC’s influenza season summary for 2007-2008 reported that 10.9% of tested influenza A (H1N1) viruses were resistant to oseltamivir. 






• Last season, CDC tested 1,769 viruses for antiviral resistance. 






• During the 2007-08 influenza season in the Northern Hemisphere, oseltamivir resistance of H1N1 viruses varied in different countries: from 0% to 70% in some European countries. 






• During the 2008 Southern Hemisphere season, oseltamivir resistance of H1N1 viruses continued to be reported, with some Southern Hemisphere countries reporting that a majority of tested A (H1N1) viruses were resistant to oseltamivir. 











• Influenza viruses can develop resistance to antiviral medications. 






• Since 2006, CDC has recommended the use of oseltamivir and zanamivir against seasonal influenza because of a high resistance to amantadine and rimantadine among influenza A (H3N2) viruses. 






• In the last two years, CDC has enhanced surveillance efforts for the detection of viruses resistant to oseltamivir (Tamiflu®) and zanamivir (Relenza®). 




• These enhanced efforts have provided CDC with the capability to detect resistant strains more quickly, and enabled CDC to monitor for changing trends over time. 






• During the 2007-08 influenza season, a small increase in the number of influenza viruses resistant to oseltamivir was observed. 


=0
A


• CDC’s influenza season summary for 2007-2008 reported that 10.9% of tested influenza A (H1N1) viruses were resistant to oseltamivir. 






• Last season, CDC tested 1,769 viruses for antiviral resistance. 






• During the 2007-08 influenza season in the Northern Hemisphere, oseltamivir resistance of H1N1 viruses varied in different countries: from 0% to 70% in some European countries. 






• During the 2008 Southern Hemisphere season, oseltamivir resistance of H1N1 viruses continued to be reported, with some Southern Hemisphere countries reporting that a majority of tested A (H1N1) viruses were resistant to oseltamivir. 









• These enhanced efforts have provided CDC with the capability to detect resistant strains more quickly, and enabled CDC to monitor for changing trends over time. 






• During the 2007-08 influenza season, a small increase in the number of influenza viruses resistant to oseltamivir was observed. 






• CDC’s influenza season summary for 2007-2008 reported that 10.9% of tested influenza A (H1N1) viruses were resistant to oseltamivir. 






• Last season, CDC tested 1,769 viruses for antiviral resistance. 






• During the 2007-08 influenza season in the Northern Hemisphere, oseltamivir resistance of H1N1 viruses varied in different countries: from 0% to 70% in some European countries. 






• During the 2008 Southern Hemisphere season, oseltam
ivir resistance of H1N1 viruses continued to be reported, with some Southern Hemisphere countries reporting that a majority of tested A (H1N1) viruses were resistant to oseltamivir. 



Current Situation 




• At this point in the season, a low level of influenza activity has been reported in the United States. As a result, very few viruses have been available for testing thus far. 

At this point in the season, a low level of influenza activity has been reported in the United States. As a result, very few viruses have been available for testing thus far. 




• At this point in the season, a low level of influenza activity has been reported in the United States. As a result, very few viruses have been available for testing thus far. 

At this point in the season, a low level of influenza activity has been reported in the United States. As a result, very few viruses have been available for testing thus far. 
1 of 3 December 19, 2008 Influenza Antiviral Resistance: Discussion Points (continued from previous page) 




• Early and limited data from this season has detected a significant increase in the proportion of influenza A (H1N1) viruses that are resistant to oseltamivir. 




• In the latest CDC FluView report published on December 19, 2008, 78 influenza viruses from 15 states had been tested for antiviral resistance. 






• This includes 50 influenza A (H1N1) viruses, 8 influenza A (H3N2 viruses) and 20 influenza B viruse
s. 






• Preliminary data show: 







o 49 of the 50 influenza A (H1N1) viruses tested were resistant to oseltamivir (98%). 





o These oseltamivir resistant viruses have been detected in 12 states, but the majority of samples have come from two states. 





o All 50 influenza A (H1N1) viruses were sensitive to zanamivir and amantadine and rimantadine. 





o All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the 
rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every in
fluenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than oth
er influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitt
ed differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been incr
easing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses ch
ange constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is 
significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared 
to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 











All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza=2
0B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






•
 Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in t
he setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and=2
0updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillan
ce data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 
=0
A


• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situatio
n very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






E2 At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible20to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 













All 50 influenza A (H1N1) viruses were sensitive to zanamivir and amantadine and rimantadine. 





o All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared 
to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising.
 Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every
 Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outl
ined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 
=0
A







All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the Un
ited States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different=2
0options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral
 medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated gui
dance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 











All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible20to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be 
during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the20resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illne
ss than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1
N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir ha
s been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 0A



• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-res
istance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 















These oseltamivir resistant viruses have been de
tected in 12 states, but the majority of samples have come from two states. 





o All 50 influenza A (H1N1) viruses were sensitive to zanamivir and amantadine and rimantadine. 





o All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance=2
0throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 





0A• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as20every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 





• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the=2
0resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illnes
s than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza 
viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in thei
r genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 











All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activi
ty are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and20rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenz
a recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatm
ent in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of20oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding20the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been re
viewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring thi
s situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to=2
0test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 













All 50 influenza A (H1N1) viruses were sensitive to zanamivir and amantadine and rimantadine. 





o All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in thei
r genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations c
onferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not=2
0surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 vi
ruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly repor
ts summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or co
mbination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine,
 were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






•=2
0Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the
 setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 











All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to=2
0test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on
 resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses 
will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–0920season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir.20






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence
 that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to osel
tamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




•
 Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 

















49 of the 50 influenza A (H1N1) viruses tested were resistant to oseltamivir (98%). 





o These oseltamivir resistant viruses have been detected in 12 states, but the majority of samples have come from two states. 





o All 50 influenza 
A (H1N1) viruses were sensitive to zanamivir and amantadine and rimantadine. 





o All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications h
ave been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be20issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will 
continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update i
nformation on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differen
tly. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, i
t’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to20oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is20no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 











All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




0 The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is sig
nificantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine.
 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options,20such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination thera
py with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data i
ndicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltami
vir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout20the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






•20Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 













All 50 influenza A (H1N1) viruses were sensitive to zanamivir and amantadine and rimantadine. 





o All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is20no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are ca
using more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 





• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly=2
0through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/f
lu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The 
fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were r
esistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses20have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as 
use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 











All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






•20Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral 
medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




•
 CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely20and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than o
ther influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmi
tted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic20makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred r
esistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 















These oseltamivir resistant viruses have been detected in 12 states, but the majority of samples have come from two states. 





o All 50 influenza A (H1N1) viruses were sensitive to zanamivir and amantadine and rimantadine. 





o All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remai
n sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different optio
ns for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of 
increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance20will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicati
ng an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




•20CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely=2
0and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this
 time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how
 common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 











All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has be
en increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza vir
uses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistanc
e is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses co
mpared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2)=2
0viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir
-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. The
se options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number o
f oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in=2
0the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 













All 50 influenza A (H1N1) viruses were sensitive to zanamivir and amantadine and rimantadine. 





o All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how
 common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest20of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruse
s are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other 
influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that20are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasin
g. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 





 The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is signi
ficantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 











All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and z
anamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in=2
0the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Di
fferent options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of 
antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and upda
ted guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, a
s every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 


0A
• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they a
re transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 







 At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 





















o 49 of the 50 influenza A (H1N1) viruses tested were resistant to oseltamivir (98%). 





o These oseltamivir resistant viruses have been detected in 12 states, but the majority of samples have come from two states. 





o All 50 influenza A (H1N1) viruses were sensitive to zanamivir and amantadine and rimantadine. 





o All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were res
istant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses 
have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as us
e of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant in
fluenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 
0A




• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update20information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenz
a season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the202008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season
 is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 











All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic 
makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred res
istance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising.=2
0Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that=2
0are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizi
ng U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination th
erapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outl
ined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different o
ptions for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting o
f increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 













All 50 influenza A (H1N1) viruses were sensitive to zanamivir and amantadine and rimantadine. 





o All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season
 is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is mo
nitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently
. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it=E
2s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantl
y through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and20one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last seas
on in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, 
the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 











All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 






o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting o
f increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1
N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indi
cating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir
-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very close
ly and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses20and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict=2
0how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the r
est of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 















These oseltamivir resistant viruses have been detected in 12 states, but the majority of samples have come from two states. 





o All 50 influenza A (H1N1) viruses were sensitive to zanamivir and amantadine and rimantadine. 





o All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




A
2 The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is signifi
cantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 0A



• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, su
ch as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy=2
0with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indic
ating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-
resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout th
e influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Re
commendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 











All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are
 transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






A
2 At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations con
ferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 





0A• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses=2
0compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not=2
0surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are publi
shed every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine,=2
0were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendati
ons. 













All 50 influenza A (H1N1) viruses were sensitive to zanamivir and amantadine and rimantadine. 





o All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Re
commendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medi
cations have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• C
DC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely an
d will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other
 influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted
 differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic ma
keup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resis
tance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 











All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May 
at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendati
ons. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) vi
ruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-re
sistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These20options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and u
pdated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance
 data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenz
a viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance 
throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 

















49 of the 50 influenza A (H1N1) viruses tested were resistant to oseltamivir (98%). 





o These oseltamivir resistant viruses have been detected in 12 states, but the majority of samples have come from two states. 





o All 50 influenza A (H1N1) viruses were sensitive to zanamivir and amantadine and rimantadine. 





o All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.
S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion=2
0of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October throu
gh mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza
 recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 2020influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 




=0
A
• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treat
ment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been rev
iewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given
 surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 











All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1
N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2
008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are caus
ing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza vi
ruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resist
ant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 





• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fa
ct that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly hig
her among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 













All 50 influenza A (H1N1) viruses were sensitive to zanamivir and amantadine=2
0and rimantadine. 





o All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given
 surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in th
e number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on20resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 
=0
A




• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s no
t possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses=2
0will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence20that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more s
evere illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 











All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly hig
her among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season20in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveil
lance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with osel
tamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2
008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant 
influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. =0
A





• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendation
s regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications ha
ve been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 















These oseltamivir resistant viruses have been detected in 12 states, but the majority of samples have come from two states. 





o All 50 influenza A (H1N1) viruses were sensitive to zanamivir and amantadine and rimantadine. 





o All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one20of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oselt
amivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the 
proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant t
o oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveill
ance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oselt
amivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 20
08 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiv
iral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circ
ulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 











All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and20update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the=2
0influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest 
of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza
 season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






•=2
0There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruse
s are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing.
 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change 
constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 













All 50 influenza A (H1N1) viruses were sensitive to zanamivir and amantadine and rimantadine. 





o All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o A
ll influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circ
ulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have20been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increa
se in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influen
za H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will co
ntinue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update inf
ormation on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1
 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 200
8–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 











All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change 
constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeu
p, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to la
st season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worl
dwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine.=2
0




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, 
such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy
 with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United 
States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different option
s for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



















o These oseltamivir resistant viruses have been detected in 12 states, but the majority of samples have come from two states. 





o All 50 influenza A (H1N1) viruses were sensitive to zanamivir and amantadine and rimantadine. 





o All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are t
ransmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• 
At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferr
ed resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






=E
2 There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses com
pared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not sur
prising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published
 every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, wer
e outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations.
 











All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given su
rveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the n
umber of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on res
istance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 


0A


• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not p
ossible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will
 be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence tha
t the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe
 illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 













All 50 influenza A (H1N1) viruses were sensitive to zanamivir and amantadine and rimantadine. 





o All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at=2
0http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations.
 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruse
s tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resist
ant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These op
tions, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updat
ed guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance d
ata indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza 
viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance thro
ughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 











All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe
 illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that=2
0they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes 
in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such muta
tions conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltam
ivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N120viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekl
y reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir20or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rim
antadine, were outlined in the 2008 influenza recommendations. 















These oseltamivir resistant viruses have been detected in 12 states, but the majority of samples have come from two states. 





o All 50 influenza A (H1N1) viruses were sensitive to zanamivir and amantadine and rimantadine. 





o All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 
0A


• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situati
on very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 







• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible
 to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes i
n their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutat
ions conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is
 not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H
1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 











All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All 
influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulati
on of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have bee
n considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase 
in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza 
H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continu
e to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update informat
ion on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 vi
ruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008009 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 













All 50 influenza A (H1N1) viruses were sensitive to zanamivir and amantadine and rimantadine. 





o All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H
1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir h
as been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 





• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-re
sistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir 
and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment 
in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of osel
tamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surv
eillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the num
ber of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 











All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008009 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is di
fferent. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses=2
0or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 







• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




E2 Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly throug
h changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher a
mong H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in 
the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 

















o All 50 influenza A (H1N1) viruses were sensitive to zanamivir and amantadine and rimantadine. 





o All 820influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase20in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza20H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season
. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regard
ing the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 
viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008=E
209 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing=2
0more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses
 or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 











All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last20season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwi
de, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday20from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in20the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 










All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United Sta
tes. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options=2
0for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medicat
ions have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance wi
ll be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 













All 50 influenza A (H1N1) viruses were sensitive to zanamivir and amantadine and rimantadine. 





o All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses
 or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 
0A




• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of
 such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamiv
ir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher=2
0among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in20the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance
 activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamiv
ir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008=2
0influenza recommendations. 











All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance wi
ll be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating=2
0an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and up
date information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the inf
luenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this t
ime, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how c
ommon H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• The
re is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses 
are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 















o All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamiv
ir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 
viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly20reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir 
or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and riman
tadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the20number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 vi
ruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 

0A



• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the=2
0use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 











All 8 influenza A (H3N2) viruses remain sensitive to oseltamivir and zanamivir. 





o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 0A





• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it9s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oselta
mivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no e
vidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season 
in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the=2
0proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from Oc
tober through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 200
8 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







=0
A




o All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United20States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different opti
ons for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral me
dications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance
 will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 









All 20 influenza B viruses remain sensitive to oseltamivir and zanamivir. 





o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every in
fluenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




•
 CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitt
ed differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At thi
s time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 











o All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations=2
0conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 







• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







All influenza A(H3N2) viruses tested were resistant to amantadine and rimantadine. 




• Weekly reports summarizing U.S. surveillance activity are published every Friday from October through mid-May at http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 
viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has b
een increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 






http://www.cdc.gov/flu/weekly/fluactivity.htm 




• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to20oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 





 Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







• The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change
 constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 



The fact that oseltamivir-resistance is significantly higher among H1N1 viruses compared to last season in the U.S. is not surprising. Worldwide, the proportion of H1N1 viruses that are resistant to oseltamivir has been increasing. 




• Influenza viruses change constantly through changes in their genetic ma
keup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 







• Influenza viruses change constantly through changes in their genetic makeup, and one of such mutations conferred resistance to oseltamivir. 






• There is no evidence that the resistant viruses are causing more severe illness than other influenza viruses or that they are transmitted differently. 






• At this 
time, it’s not possible to predict how common H1N1 viruses will be during the rest of the 2008–09 season, as every influenza season is different. 




• CDC is monitoring this situation very closely and will continue to test influenza viruses and update information on resistance throughout the influenza season. 






• Recommendations regarding the use of antiviral medications have been reviewed and updated guidance will be issued given surveillance data indicating an increase in the number of oseltamivir-resistant influenza H1N1 viruses in the United States. 






• Different options for antiviral treatment in the setting of increased circulation of oseltamivir-resistant H1N1 viruses have been considered. These options, such as use of zanamivir or combination therapy with oseltamivir and rimantadine, were outlined in the 2008 influenza recommendations. 


2 of 3 December 19, 2008 Influenza Antiviral Resistance: Discussion Points (continued from previous page) 




• CDC’s interim guidance on the use of influenza antiviral medications in the United States for the 2008-09 season will be issued in a Health Alert Advisory on December 19. This revised guidance will be available at www.cdc.gov/flu. 






• Clinicians should be aware that revised interim guidance on the use of antiviral medications is being provided by CDC for the current influenza season and will be available at www.cdc.gov/flu. 






• Information from local or state virus=2
0surveillance data and laboratory testing can help clinicians in selecting appropriate antiviral medications for their patients. 






• When influenza A (H1N1) virus infection or exposure is suspected, zanamivir or a combination of oseltamivir and rimantadine are more appropriate options than oseltamivir alone. 




• CDC is working to communicate this new guidance broadly through a clinician communications campaign to alert health care providers to the change in recommendations for antiviral medications this season. 




• Influenza vaccines are expected to be effective in preventing or reducing the severity of infection with currently circulating influenza viruses, including oseltamivir-resistant influenza A (H1N1) 



Influenza vaccines are expected to be effective in preventing or reducing the severity of infection with currently circulating influenza viruses, including oseltamivir-resistant influenza A (H1N1) 
3 of 3 December 19, 2008 

 
From: folk.devil at hotmail.com
To: gathering at misera.net
Date: Tue, 14 Jul 2009 10:17:12 -0700
Subject: Re: [kj] mark of the beast closer than expected

Compulsory vaccination is suggested for the last Phase of an epidemic.
Another strangeity is that H1N1 is resistant to Tamiflu.
http://www.health.state.nm.us/FLU/docs/Antiviral%20Resistance_Background%20and%20Current%20Situation_partners_12_19.pdf
 
From: dpeace at bigfoot.com
To: gathering at misera.net
Date: Tue, 14 Jul 2009 18:10:26 +0100
Subject: Re: [kj] mark of the beast closer than expected



Have you forgotten your meds again, Stephen?=0
A
 

Darren

Hungerford, UK

 

(PS No, I’ve not heard of any fast track programme. Link?)

 



From: gathering-bounces at misera.net [mailto:gathering-bounces at misera.net] On Behalf Of Stephen Lawrence
Sent: 14 July 2009 5:52 PM
To: gathering at misera.net
Subject: [kj] mark of the beast closer than expected



 

anyone aware of the SWINE FLU fast track vaccination programme ?
looks like the conspiracy theorists were right 
they are talking about jab or jail 
hope my u s trip isn't cut short 
how the fuck can you clinically trial a vaccine in a coupla months ?
 
oh and it was a MOCK ONE btw 
not the shit they wanna pump in our vains 
swine flu my arse 
more like de- population
and surreptitious tagging 
welcome to minority report world 



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