WHO Announces 2026 Southern Hemisphere Flu Vaccine Composition, drops Further Yamagata Lineage Updates
Geneva, Switzerland – The World Health Association (WHO) today released its recommendations for the influenza vaccine composition intended for use during the 2026 influenza season in the southern hemisphere. The declaration followed a four-day consultation involving experts from WHO Collaborating Centres and Essential Regulatory Laboratories, convened to review the latest global influenza surveillance data.
These twice-yearly consultations – one for the northern hemisphere and one for the southern – are critical for maintaining vaccine effectiveness against the constantly evolving influenza viruses and protecting public health worldwide. The recommendations are based on data collected and analyzed by the WHO Global Influenza Surveillance and Response System (GISRS) and its collaborators.
for the 2026 southern hemisphere season,the WHO recommends trivalent influenza vaccines contain the following:
For egg-based vaccines:
* An A/Missouri/11/2025 (H1N1)pdm09-like virus
* An A/Singapore/GP20238/2024 (H3N2)-like virus
* A B/Austria/1359417/2021 (B/Victoria lineage)-like virus
for cell culture-,recombinant protein- or nucleic acid-based vaccines:
* an A/Missouri/11/2025 (H1N1)pdm09-like virus
* An A/Sydney/1359/2024 (H3N2)-like virus
* A B/Austria/1359417/2021 (B/Victoria lineage)-like virus
Significantly,the WHO advisory committee has reaffirmed its position – held consistent across the last four recommendations since September 2023 – that including a B/Yamagata lineage antigen in vaccines is no longer necessary. While some quadrivalent vaccines still in production contain a fourth component targeting the B/Yamagata lineage (specifically, a B/Phuket/3073/2013-like virus), the WHO will no longer issue updated recommendations for this component.
Beyond seasonal vaccine composition, the WHO also announced updated recommendations for developing new candidate vaccine viruses to address potential zoonotic influenza threats, bolstering pandemic preparedness efforts.
These recommendations will serve as the foundation for national and regional regulatory authorities, and also pharmaceutical manufacturers, in the development, production, and licensing of influenza vaccines for the upcoming season.
