THE INFLUENZA vaccine composition for the 2026–2027 northern hemisphere season has now been set, following a detailed review of global surveillance data coordinated by World Health Organization (WHO). Seasonal influenza, a highly contagious acute respiratory infection, causes up to 650,000 respiratory deaths worldwide each year, making timely vaccine updates essential for public health planning.
Global Surveillance Highlights Rapid Viral Evolution
The recommendation follows a 4-day consultation involving experts from Global Influenza Surveillance and Response System, the longstanding global platform that tracks influenza activity across regions. The system monitors viral evolution throughout the year, enabling clinicians and vaccine developers to adjust formulations ahead of each influenza season.
This year’s update was driven largely by the global spread of a new A(H3N2) variant, classified as J.2.4.1 or “subclade K”, which emerged in August 2025. Its rapid expansion contributed to early and unusually intense influenza activity in several countries. Influenza A viruses remained dominant overall, with relatively few detections of influenza B, and no confirmed cases of B/Yamagata since early 2020.
Zoonotic Influenza Under Close Watch
Experts also assessed zoonotic, or animal-derived, influenza viruses, which remain a pandemic threat. Since September 2025, 25 human cases were reported across six countries, with infections linked primarily to exposure to infected animals or contaminated environments. No human-to-human transmission has been identified. In preparation for potential future threats, the panel advised developing a new candidate vaccine virus targeting A(H9N2).
Recommendations for the 2026–27 Influenza Vaccine
For the upcoming season, the recommended influenza vaccine composition includes updated strains tailored for egg-based and cell- or recombinant-based vaccine platforms. These include A(H1N1)pdm09-like, A(H3N2)-like, and B/Victoria lineage-like viruses, selected for their close match to circulating strains.
Implications for Clinicians and Public Health
For healthcare professionals, the updated composition reinforces the importance of vaccination in preventing severe influenza, especially among high-risk groups. The annual update ensures vaccines offer the closest possible protection against current and emerging strains, supporting global efforts to reduce hospitalisations, severe disease and mortality.
Reference
World Health Organization (WHO). Recommendations for influenza vaccine composition for the 2026-2027 northern hemisphere season. 2026. Available at: https://www.who.int/news/item/27-02-2026-recommendations-for-influenza-vaccine-composition-for-the-2026-2027-northern-hemisphere-season. Last accessed: 04 March 2026.
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