2009 H1N1 Pandemic Influenza

H1N1 Virus2009 H1N1 was first detected in the United Statesin April 2009 and on June 11, 2009 the World Health Organization declared it a global pandemic. 2009 H1N1 influenza became the fourth pandemic since the pandemic of 1918.

This virus was a unique combination of influenza virus genes never previously identified in either animals or people. The virus genes were a combination of genes most closely related to North American swine-lineage H1N1 and Eurasian lineage swine-origin H1N1 influenza viruses. Because of this, initial reports referred to the virus as a swine-origin influenza virus. However, investigations of initial human cases did not identify exposures to pigs and quickly it became apparent that this new virus was circulating among humans and not among U.S. pig herds.

By the time the pandemic was declared over (August 2010), approximately 18,000 people worldwide had died from the disease.

Current information on H1N1

Current Information on H1N1 from the Pan American Heath Organization.

Learn more about H1N1 response efforts from NIPHC health departments

General information about 2009 H1N1

2009 H1N1