What is H1N1 (swine) flu?

Novel H1N1 (referred to as “swine flu” ) is a new influenza virus causing illness in people. This virus was first detected in people in the United States in April 2009. This virus is spreading from person-to-person worldwide, probably in much the same way that regular seasonal influenza viruses spread. On June 11, 2009, the World Health Organization (WHO) signaled that a pandemic of novel H1N1 flu was underway.

Last Reviewed: 08/16/2009

• What are the signs and symptoms of H1N1 (swine) flu in people?
• What investigations are taking place about the H1N1 swine flu outbreak?
• How is the U.S. government responding to the spread of the new H1N1 flu?

• H1N1 Flu