What are the vaccine viruses for the 2023–24 influenza season?

Vaccine viruses differ by the type of vaccine (egg-based or non-egg-based), but they protect against the same strains of circulating viruses.

For the 2023–24 season, U.S. egg-based influenza vaccines (vaccines other than ccIIV4 and RIV4) will contain hemagglutinin (HA) derived from:
• an influenza A/Victoria/4897/2022(H1N1)pdm09-like virus,
• an influenza A/Darwin/9/2021 (H3N2)-like virus,
• an influenza B/Austria/1359417/2021 (Victoria lineage)-like virus, and
• an influenza B/Phuket/3073/2013(Yamagata lineage)-like virus.

For the 2023–24 season, U.S. cell culture–based inactivated (ccIIV4) and recombinant (RIV4) influenza vaccines will contain HA derived from:
• an influenza A/Wisconsin/67/2022(H1N1)pdm09-like virus,
• an influenza A/Darwin/6/2021 (H3N2)-like virus,
• an influenza B/Austria/1359417/2021 (Victoria lineage)-like virus, and
• an influenza B/Phuket/3073/2013 (Yamagata lineage)-like virus.