What is H1N1 (swine flu) and how is it different from seasonal flu?
Seasonal flu comes back in slightly different forms each year. But the H1N1 flu (swine flu) is a new influenza virus causing illness in people. This new virus was first detected in people in the United States in April 2009. This virus spreads from person to person, in much the same way that regular seasonal influenza viruses spread. Because H1N1 is a new strain of influenza, most people have little immunity to it either naturally or from previous flu vaccines.
