WHO recommends six specific strains for 2026-27 Northern Hemisphere flu vaccines
WHO announced new strain recommendations after a four-day review, listing platform-specific candidates to guide vaccine manufacture and regulatory licensing.
After a four-day consultation of global surveillance data, the World Health Organization recommended the viral composition for 2026-27 Northern Hemisphere influenza vaccines, naming distinct candidate strains for egg-based and cell culture, recombinant protein and nucleic acid vaccines. The guidance, issued 27 February 2026, is intended to steer manufacturers and national regulators as they prepare vaccines for the coming season.
For egg-based vaccines WHO advised inclusion of an A/Missouri/11/2025 (H1N1)pdm09-like virus, an A/Darwin/1454/2025 (H3N2)-like virus, and a B/Tokyo/EIS13-175/2025 (B/Victoria lineage)-like virus. For cell culture, recombinant protein and nucleic acid platforms the agency recommended an A/Missouri/11/2025 (H1N1)pdm09-like virus, an A/Darwin/1415/2025 (H3N2)-like virus, and a B/Pennsylvania/14/2025 (B/Victoria lineage)-like virus. WHO materials explicitly list different A/Darwin and B/Victoria isolate identifiers by manufacturing platform; the A/Missouri/11/2025 (H1N1)pdm09-like virus is common to both recommendations.
WHO said the decisions followed analysis by the Global Influenza Surveillance and Response System, which convened experts from WHO Collaborating Centres and Essential Regulatory Laboratories to review genetic and antigenic data, including antigenic cartography and phylogenetic analysis performed by the University of Cambridge. The agency acknowledged contributions from National Influenza Centres, non-GISRS laboratories, the World Organization for Animal Health and the Food and Agriculture Organization of the United Nations Network of Expertise on Animal Influenza.
Surveillance cited by WHO showed influenza A viruses predominated during the review window, with circulating A(H3N2) and A(H1N1) variants observed and only low levels of B/Victoria lineage viruses. The agency additionally noted that no cases of B/Yamagata lineage viruses have been recorded since March 2020. WHO framed the update as necessary because influenza viruses change constantly and vaccine composition must be refreshed accordingly.
WHO emphasized practical timing constraints. The agency noted that vaccine strain decisions are made months in advance to accommodate manufacturing and distribution lead times, and that national regulatory authorities and manufacturers use WHO recommendations to develop, produce and license vaccines. WHO also reiterated that a separate consultation will be held in September 2026 to recommend composition for the Southern Hemisphere 2027 season and that guidance for tropical and subtropical country choices is available on the WHO Global Influenza Programme website.
The consultation followed WHO governance procedures for external advisers. Directors and experts from relevant collaborating centres and regulatory laboratories completed WHO declarations of interest before the meeting, and declared interests were disclosed at the start of the consultation; the document states that “Advisers declared the following personal current or recent (within the past 4 years) financial or other …” as recorded in consultation materials.
“Season after season, constantly evolving influenza viruses circulate globally, reminding us how interconnected our world is. Shared risks require shared action,” Dr. Tedros Adhanom Ghebreyesus, WHO Director-General, said in the agency’s press release on 27 February 2026.
WHO listed mediainquiries@who.int as the contact for further information. National agencies and manufacturers will now use the platform-specific recommendations to finalize candidate vaccine viruses, initiate production runs and seek regulatory approvals ahead of the Northern Hemisphere 2026-27 influenza season.
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