Content on this page was developed during the 2009-2010 H1N1 pandemic and has not been updated.
- The H1N1 virus that caused that pandemic is now a regular human flu virus and continues to circulate seasonally worldwide.
- The English language content on this website is being archived for historic and reference purposes only.
- For current, updated information on seasonal flu, including information about H1N1, see the CDC Seasonal Flu website.
Information about the 2009 H1N1 Virus
November 25, 2009 10:00 AM ET
- Origin of the 2009 H1N1 Virus: Questions and Answers
- Reports of Small Changes to Some 2009 H1N1 Viruses: Questions & Answers
- Images of the 2009 H1N1 Influenza Virus
- General Information About Influenza Viruses
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