The United States will participate in a World Health Organization meeting later this month focused on determining the composition of influenza vaccines for the upcoming season, underscoring continued engagement in global vaccine guidance despite recent shifts in U.S.–WHO relations.
The meeting, scheduled for February 23–26 in Istanbul, Türkiye, is part of the WHO’s twice-annual consultation process that reviews global influenza virus surveillance data and provides recommendations on which virus strains should be included in vaccines for the 2026–27 northern hemisphere influenza season.
The consultations draw on data from the WHO Global Influenza Surveillance and Response System, a network of more than 150 laboratories in over 130 countries that tracks circulating seasonal and zoonotic influenza viruses.
U.S. participation involves contributing epidemiological and laboratory surveillance findings, which help shape strain selection discussions that occur months before vaccine manufacturing begins. Vaccine composition recommendations issued by WHO are widely used by national regulatory agencies and manufacturers to ensure immunisation strategies match current virus circulation patterns.
Annual influenza vaccine formulation updates are necessary because influenza viruses evolve rapidly through small genetic changes, a process known as antigenic drift, which can affect vaccine effectiveness if compositions are not updated regularly.
Global coordination allows stakeholders to align on the most relevant virus strains for production timelines.
Selection of influenza vaccine components has long relied on international collaboration. WHO convenes expert advisory groups twice a year — for the southern and northern hemisphere seasons — to analyse antigenic and genetic characteristics of circulating viruses and issue guidance that informs national vaccination policies.
The U.S. engagement in these consultations continues even as the country recently formalised its withdrawal from the WHO, highlighting the ongoing importance placed on sharing surveillance data and participating in technical deliberations that have significant implications for public health preparedness ahead of the next influenza season.
