Information for the 2024-2025 Flu Season

The composition of flu vaccines has been updated. Flu vaccines for the U.S. 2024-2025 season will contain the following:

Egg-based vaccines

  • an A/Victoria/4897/2022 (H1N1)pdm09-like virus;
  • an A/Thailand/8/2022 (H3N2)-like virus; and (Updated)
  • a B/Austria/1359417/2021 (B/Victoria lineage)-like virus.

Cell- or recombinant-based vaccines

  • an A/Wisconsin/67/2022 (H1N1)pdm09-like virus;
  • an A/Massachusetts/18/2022 (H3N2)-like virus; and (Updated)
  • a B/Austria/1359417/2021 (B/Victoria lineage)-like virus.

All flu vaccines for the 2024-2025 season are anticipated to be trivalent in the United States. Trivalent flu vaccines are formulated to protect against three flu viruses (an A(H1N1) virus, an A(H3N2) virus, and a B/Victoria virus). Both trivalent and quadrivalent flu vaccines are expected to offer similar protection against the flu viruses they protect against. B/Yamagata flu viruses have not circulated in the population after March 2020, so protection from trivalent and quadrivalent flu vaccines is expected to be similar. More information about trivalent flu vaccines is available.