What is the H1N1 flu, or swine flu?
• Influenza—also called “the flu”—is a contagious illness caused by a virus, which is a type of germ.1 • You may see the flu described as “seasonal flu” because, in the United States, people usually get the flu during the fall and winter months.2 • Flu viruses change as they pass from person to person. Over time, new strains of the flu virus also develop in animals, such as pigs, and these flu viruses are able to cause illness in people.
