The seasonal flu shot is a yearly vaccine administered to protect against the flu, or influenza. In the United States, flu shots are recommended for everyone ages 6 months and older, according to the Centers for Disease Control and Prevention.

The flu can be a very serious illness, especially in young children, adults ages 65 and over, those with underlying health conditions, and pregnant women. The flu shot is the best way to protect yourself and family from the flu, the CDC says.