Influenza (flu) is a contagious respiratory illness caused by influenza viruses. It can cause mild to severe illness. Serious outcomes of flu infection can result in hospitalization or death. Influenza Vaccine (commonly known as “the flu shot”) is recommended yearly by the CDC for everyone 6 months and older. Flu vaccine is the best way to protect against flu. Vaccination can reduce flu illnesses, doctors’ visits, and missed work and school, as well as prevent hospitalizations.