Seasonal Influenza Vaccines
The influenza vaccine — the best protection against seasonal influenza — is approved for use annually in people 6 months and older. It is safe for both healthy individuals and those with chronic medical conditions and is available as a flu shot or nasal spray.
Each year, the specific viruses in the vaccine are chosen for vaccine effectiveness (VE) based on international surveillance and scientists' estimations about which types and strains will circulate in a given year. The seasonal flu shot and nasal spray protect against the most prevalent influenza viruses in circulation during the flu season. Both trivalent (three-strain) and quadrivalent (four-strain) influenza vaccines are indicated to help prevent, mitigate, and treat influenza and influenza-related illnesses.