Home > Encyclopedia of Children's Health > Flu Vaccine

Definition

The flu vaccine protects a person against getting influenza, caused by the influenza virus. It is administered either by injection or by inhalation.

Description

There are two types of flu vaccine. Live attenuated influenza vaccine (LAIV) was first approved for use in 2003. It contains live, but weakened, influenza virus and is administered as a nasal spray. Inactivated influenza vaccine contains killed viruses and is given by intramuscular injection.

Because influenza changes from year to year, a flu shot, unlike other types of vaccinations, is required every year. Each year, the United States Centers for Communicable Disease Control predicts the strains of influenza that are likely to appear in...