On Mar. 13, 2025, the U.S. Food and Drug Administration (FDA) announced recommendations to vaccine manufacturers for the virus strains to be used in influenza (flu) vaccines for the 2025-2026 U.S. flu season following a thorough and comprehensive review of U.S. and global surveillance data.

Trivalent seasonal influenza vaccines include two influenza A subtype viruses (H1N1 and H3N2) and one influenza type B virus. Influenza virus strains were selected based on the influenza vaccine production method: egg-based and cell- or recombinant-based.

The FDA has informed the manufacturers of FDA-approved seasonal influenza vaccines of these recommendations. The FDA anticipates that there will be an adequate and diverse supply of approved trivalent seasonal influenza vaccines for the 2025-2026 U.S. influenza season.