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.