An emerging influenza variant is spreading, but vaccination remains our strongest defense, says the World Health Organization (WHO).
Influenza and other respiratory illnesses are on the rise. Dr. Wenqing Zhang, who leads the Global Respiratory Threats team within the WHO’s Department of Epidemic and Pandemic Threats Management, noted in Geneva that this year has seen the appearance and rapid spread of a new AH3N2 virus subclade.
The fresh variant, designated J.2.4.1 or subclade K, was first detected in Australia and New Zealand in August and has since been identified in more than 30 countries, according to Dr. Zhang.
DNA that keeps mutating
Despite this genetic shift driving noticeable viral evolution, current data do not indicate a rise in disease severity, Dr. Zhang explained. Influenza viruses continually evolve, which is why the seasonal vaccine composition is updated regularly.
WHO monitors these genetic changes, evaluates the public-health risks they pose, and issues vaccine recommendations twice a year through the Global Influenza Surveillance and Response System (GISRS), a long-standing collaboration with global experts, Dr. Zhang added.
The new variant has not been incorporated into the latest Northern Hemisphere vaccine formulations, the WHO expert clarified.
Nonetheless, early data suggest that existing seasonal vaccines still provide protection against severe illness and can reduce hospitalizations, she noted.
Global estimates place seasonal influenza at about one billion cases annually, with up to five million cases of severe respiratory disease and as many as 650,000 deaths from influenza-related respiratory conditions each year.
Staying protected
Vaccination remains the most effective defense, especially for high-risk groups and their caregivers, Dr. Zhang emphasized.
Early vaccine effectiveness estimates against the new variant, reported in the United Kingdom, appear promising. The data indicate the vaccine is roughly 75% effective against severe disease and hospitalization in children and around 35% in adults.
With the holiday season likely to drive another wave of respiratory illnesses, she urged proactive planning and preparedness, including boosting vaccination uptake and strengthening health-system readiness.
Countries were urged to enhance laboratory diagnostics, maintain year‑round disease surveillance, and participate in GISRS surveillance networks.
Global surveillance stays essential
GISRS comprises influenza centers in about 130 countries and a network of a dozen reference laboratories.
When asked if the United States will remain part of GISRS next year after its planned withdrawal from WHO on January 22, 2026, Dr. Zhang stressed that, from a flu- and respiratory-surveillance standpoint, participation by all nations remains crucial. Predicting where and when the next pandemic strain will emerge is impossible, and the interval between emergence, detection, characterization, and vaccine incorporation can significantly affect lives saved.
In closing, she underscored that broad international collaboration in surveillance, preparedness, and response is vital to mitigating future influenza and other respiratory threats.
