The periodic replacement of virus strains contained in influenza vaccine is necessary because of the constant evolution of influenza viruses, which can change their antigenic and genetic characteristics. The World Health Organization (WHO) recommends the following influenza vaccine composition information.
Seasonal Influenza Risk Groups
The WHO recommends that trivalent vaccines for use in the 2023-2024 northern hemisphere influenza season contain the following:
Egg-based vaccines
- an A/Victoria/4897/2022 (H1N1)pdm09-like virus;
- an A/Darwin/9/2021 (H3N2)-like virus; and
- a B/Austria/1359417/2021 (B/Victoria lineage)-like virus.
Cell culture- or recombinant-based vaccines
- an A/Wisconsin/67/2022 (H1N1)pdm09-like virus;
- an A/Darwin/6/2021 (H3N2)-like virus; and
- a B/Austria/1359417/2021 (B/Victoria lineage)-like virus
For quadrivalent egg- or cell culture-based or recombinant vaccines for use in the 2023-2024 northern hemisphere influenza season, the WHO recommends inclusion of the following as the B/Yamagata lineage component:
- a B/Phuket/3073/2013 (B/Yamagata lineage)-like virus.
Development and production of influenza vaccines, planning for their supplies and use as well as provision of other respective health care resources are essential components of a comprehensive seasonal and pandemic influenza response. 2
WHO (24 February 2023) Frequently asked questions
Southern Hemisphere 2024
The WHO recommends that trivalent vaccines for use in the 2024 southern hemisphere influenza season contain the following:
Egg-based vaccines
- an A/Victoria/4897/2022 (H1N1)pdm09-like virus;
- an A/Thailand/8/2022 (H3N2)-like virus; and
- a B/Austria/1359417/2021 (B/Victoria lineage)-like virus.
Cell culture- or recombinant-based vaccines
- an A/Wisconsin/67/2022 (H1N1)pdm09-like virus;
- an A/Massachusetts/18/2022 (H3N2)-like virus; and
- a B/Austria/1359417/2021 (B/Victoria lineage)-like virus.
For quadrivalent egg- or cell culture-based or recombinant vaccines for use in 2024 southern hemisphere influenza season, the WHO recommends inclusion of the following B/Yamagata lineage component:
- a B/Phuket/3073/2013 (B/Yamagata lineage)-like virus.