The World Health Organization (WHO) today issued its recommendations for influenza vaccine composition for the 2026-2027 northern hemisphere influenza season, following a four-day consultation involving global influenza surveillance data. The recommendations aim to ensure that flu vaccines are closely matched to circulating viruses, maximizing protection against severe illness and death.
The WHO’s recommendations are crucial for national vaccine regulatory agencies and pharmaceutical companies as they develop and produce vaccines for the upcoming season. The process of regular updates is essential due to the constant evolution of influenza viruses.
“Season after season, constantly evolving influenza viruses circulate globally, showing us how connected our world is. Shared risks require shared action,” stated Dr. Tedros Adhanom Ghebreyesus, WHO Director-General. He emphasized the importance of the Global Influenza Surveillance and Response System (GISRS) and its partners in providing the data necessary to update vaccines and protect communities.
The recent emergence of a distinct variant of the A(H3N2) virus, classified as J.2.4.1 or “subclade K,” in August 2025 significantly impacted influenza patterns. This variant spread rapidly, contributing to an earlier start to the influenza season in many countries and higher-than-usual levels of activity. Subclade K became the dominant strain reported across regions.
Whereas influenza A viruses were predominant other variants of A(H3N2) and A(H1N1) were too recorded. Influenza B viruses, specifically the B/Victoria lineage, were detected at low levels, while no cases of the B/Yamagata lineage have been reported since March 2020.
Experts also assessed influenza viruses circulating in animals, particularly those with the potential to infect humans. Since September 23, 2025, WHO has been notified of 25 human infections with zoonotic influenza viruses from six countries. These cases primarily involved exposure to infected animals or contaminated environments, with no evidence of human-to-human transmission reported.
The WHO meeting included a review of these zoonotic viruses and the selection of new candidate vaccine viruses (CVVs) for potential pandemic preparedness. Experts recommended the development of a new CVV for an A(H9N2) virus.
For the 2026-2027 northern hemisphere influenza season, the WHO recommends the following vaccine compositions:
Egg-based vaccines:
- A/Missouri/11/2025 (H1N1)pdm09-like virus
- A/Darwin/1454/2025 (H3N2)-like virus
- B/Tokyo/EIS13-175/2025 (B/Victoria lineage)-like virus
Cell culture-, recombinant protein- or nucleic acid-based vaccines:
- A/Missouri/11/2025 (H1N1)pdm09-like virus
- A/Darwin/1415/2025 (H3N2)-like virus
- B/Pennsylvania/14/2025 (B/Victoria lineage)-like virus
Seasonal influenza is a significant global health concern, causing an estimated 290,000 to 650,000 respiratory deaths annually, from around a billion cases each year, including 3–5 million severe illnesses. The WHO’s GISRS, established in 1952, continues to serve as the longest-standing global platform for systematic disease surveillance.
The United States participated in the influenza vaccine meeting, according to a statement released by The Hill.
