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.

2009 H1N1 Flu: Situation Update

The final CDC influenza activity report for the 2009-10 flu season was published on May 28, 2010. While influenza surveillance takes place year-round, official reporting (FluView publication) routinely happens between October and May to coincide with normally occurring influenza activity in the United States. Unless unusual influenza activity occurs over the summer of 2010, surveillance reports for all influenza viruses for the 2010-2011 season will resume in October 2010 and appear on the seasonal influenza website.

The 2009 H1N1 web pages, including situation updates, will be archived for historical purposes.