Skip to main content

Influenza

Influenza (also called "flu") is a type of respiratory disease caused by influenza viruses. Two types of influenza, A and B, cause outbreaks in people. Influenza can be mild or severe.

The seasonal influenza viruses are detected year-round in the United States, but they are usually most active during the fall and winter. This is called "flu season."

Many people use the word "flu" when talking about a severe cold or a stomach virus, but these are not the same as influenza.