Influenza Vaccines Overview

Information

The flu is a contagious respiratory disease caused by an influenza virus. In the U.S., flu outbreaks typically occur in winter months. Symptoms include fever , chills, sore muscles, and cough. Thousands of people in the U.S. die each year from the flu or its complications. Most of those who die are the elderly, young children, or people with compromised immune systems.

See article on the flu for more information.

The viruses that typically cause the flu are primarily categorized as influenza type A or type B. Influenza type B does not change much over time, but type A can mutate rapidly. Therefore, a new form of the flu vaccine must be developed each year to protect people for the exact strain that is expected to be most prevalent.

All the influenza viruses in the flu shot are killed (inactive), so it is not possible to get the flu from this type of vaccine. However, some people ...