Recommended influenza vaccine strains (Northern Hemisphere, 2025–2026)
Use trivalent vaccines containing: A(H1N1) A/Victoria/4897/2022-like (egg) or A/Wisconsin/67/2022-like (cell/recombinant); A(H3N2) A/Croatia/10136RV/2023-like (egg) or A/District of Columbia/27/2023-like (cell/recombinant); and B/Victoria B/Austria/1359417/2021-like. 1, 2
- Platform specifics:
Rationale and practice notes (morbidity, mortality, QOL focus)
- AAP 2025–2026 and ACIP 2025–26 guidelines are the most recent, highest-quality sources and align on these strains; all U.S. vaccines this season are trivalent, with H3N2 updated from last season to improve clinical protection and reduce severe outcomes 1, 2.
- H3N2 subclade K predominated in many regions; despite some antigenic drift, vaccines with the updated H3N2 component showed moderate effectiveness against outpatient illness and likely mitigate hospitalizations and deaths—supporting use of the recommended composition to protect QOL and reduce morbidity/mortality 3.
Pitfalls and caveats
- Do not wait for a specific brand; use any age-appropriate trivalent product with the above strains to avoid missed vaccination opportunities 1, 2.
- Expect egg-based versus cell/recombinant strain name differences; both are antigenically matched per platform and acceptable 1.
- In the U.S., B/Yamagata is no longer included; quadrivalents may still exist outside the U.S.—ensure trivalent use domestically 4, 1.
- Monitor local guidance for thimerosal-free single-dose recommendations (ACIP update) when relevant to setting and population logistics 2.