Influenza definition - Medical and health information on the common cold and flu

Our Influenza Main Article provides a comprehensive look at the who, what, when and how of Influenza

Influenza: The flu is caused by viruses that infect the respiratory tract which are divided into three types, designated A, B, and C. Most people who get the flu recover completely in 1 to 2 weeks, but some people develop serious and potentially life-threatening medical complications, such as pneumonia. Much of the illness and death caused by influenza can be prevented by annual influenza vaccination.