#17,923
Twice each year international influenza experts meet to discuss recent developments in human and animal influenza viruses around the world, and to decide on the composition of the next influenza season’s flu vaccine. Due to the time it takes to manufacture and distribute a vaccine, decisions on which strains to include must be made six months in advance.
Which means the composition of the northern hemisphere’s vaccine must be decided upon in February of each year, while decisions on the southern hemisphere’ vaccine are made in September.
Today the WHO released their recommendations for the composition of this fall's 2024-2025 Northern Hemisphere flu vaccine, which mirrors the recommendations made last September for the 2024 flu vaccine in the Southern Hemisphere.
Of particular note, inclusion of the B/Yamagata lineage component is no longer recommended, as explained in the following FAQ.
Why is a B/Yamagata lineage vaccine component no longer needed?
There have been no confirmed naturally occurring B/Yamagata lineage virus detections after March 2020. Further to the WHO September 2023 recommendation, it remains the opinion of the WHO influenza vaccine composition advisory committee that the B/Yamagata lineage antigen should be excluded from influenza vaccines as it is no longer needed. National or regional authorities should make decisions regarding the transition to trivalent influenza vaccines in their jurisdictions
A brief overview, and a link to a more detailed report follow:
Recommended composition of influenza virus vaccines for use in the 2024-2025 northern hemisphere influenza season
23 February 2024
| Meeting reportOverview
The WHO recommends that trivalent vaccines for use in the 2024-2025 northern 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 the 2024-2025 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.
