From Centers of Disease Control and Prevention:

H1N1 Flu (Swine Flu) and You*

May 27, 2009 12:45 PM ET

Novel H1N1 Flu

What is H1N1 (swine flu)?
H1N1 (referred to as “swine flu” early on) is a new influenza virus causing illness in people. This new virus was first detected in people in the United States in April 2009. Other countries, including Mexico and Canada, have reported people sick with this new virus. This virus is spreading from person-to-person, probably in much the same way that regular seasonal influenza viruses spread.

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