Influenza A viruses dominated most regions in early 2026, while WHO says vaccine updates remain essential as flu viruses evolve.
By Bunmi Yekini
The World Health Organization (WHO) has recommended the influenza virus strains to be used in vaccines for the 2027 southern hemisphere flu season, following its latest review of global surveillance data.
The recommendations are aimed at ensuring vaccines are closely matched to the influenza viruses expected to circulate during the next season.
WHO said influenza A(H1N1)pdm09, A(H3N2) and influenza B viruses circulated across all regions between February and August 2026, causing illness and hospitalisations.
Influenza A viruses were the most common in most regions, while influenza B dominated in Northern and Western Africa, North America and Eastern Asia, the agency said.
For egg-based vaccines, WHO recommended 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- or nucleic acid-based vaccines, WHO recommended A/Missouri/11/2025 (H1N1)pdm09-like, A/Darwin/1415/2025 (H3N2)-like and B/Pennsylvania/14/2025 (B/Victoria lineage)-like viruses.
WHO updates its influenza vaccine recommendations twice a year after experts review virus surveillance data collected through its Global Influenza Surveillance and Response System and other sources.
Maria Van Kerhove, WHO’s director for epidemic and pandemic management, said the global surveillance network enabled countries and laboratories to share virus data and expertise needed to guide timely vaccine decisions.
WHO also reviewed influenza viruses circulating in animals, including viruses that have infected humans, because of their potential to cause future pandemics.
The agency said its experts selected candidate vaccine viruses from contemporary zoonotic influenza strains that could be used to rapidly develop vaccines if a pandemic threat emerges.
WHO’s recommendations are used by national regulatory agencies and vaccine manufacturers to develop, produce and license vaccines ahead of each influenza season.