As I understand it…the northern and southern hemisphere depend on each other in determining which strain to include in the vaccine. So the north looks at what has happened in the south to determine what to include in the north for the next season right? So I wonder…why do this? Why not just include all 14 of the known strains and be done with it? Is there an incompatibility that we don’t know about? Asking for a friend…
Because we haven’t yet made a vaccine that is capable of targeting multiple strains effectively much less cost effectively. There are a few multivalent flu vaccines in clinical trials but it’ll take a while for those to fully pan out.
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.
As a result of the meeting with the federal partners, the FDA recommends that the trivalent formulation of egg-based influenza vaccines for the 2025-2026 U.S. influenza season contain the following:
- an A/Victoria/4897/2022 (H1N1)pdm09-like virus;
- an A/Croatia/10136RV/2023 (H3N2)-like virus; and
- a B/Austria/1359417/2021 (B/Victoria lineage)-like virus.
The FDA recommends that the trivalent formulation of cell- or recombinant-based influenza vaccines for the 2025-2026 U.S. influenza season contain the following:
- an A/Wisconsin/67/2022 (H1N1)pdm09-like virus;
- an A/District of Columbia/27/2023 (H3N2)-like virus; and
- a B/Austria/1359417/2021 (B/Victoria lineage)-like virus.
As I understand it…the northern and southern hemisphere depend on each other in determining which strain to include in the vaccine. So the north looks at what has happened in the south to determine what to include in the north for the next season right? So I wonder…why do this? Why not just include all 14 of the known strains and be done with it? Is there an incompatibility that we don’t know about? Asking for a friend…
Because we haven’t yet made a vaccine that is capable of targeting multiple strains effectively much less cost effectively. There are a few multivalent flu vaccines in clinical trials but it’ll take a while for those to fully pan out.
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