A new influenza variant is spreading, but vaccination remains our strongest defense, according to the World Health Organization (WHO).
Health researchers note that flu and other respiratory illnesses are circulating more widely this season. Dr. Wenqing Zhang, head of the Global Respiratory Threats unit within WHO’s Department of Epidemic and Pandemic Threats Management, highlighted in Geneva that the year has seen the emergence and rapid growth of a fresh AH3N2 virus sublineage.
This newly identified variant, either labeled J.2.4.1 or subclade K, first appeared in Australia and New Zealand in August and has since been detected in more than 30 countries, Dr. Zhang explained.
DNA is constantly changing in influenza viruses, a phenomenon that can yield notable evolutionary shifts even if current illness severity does not appear to worsen, she added. Because influenza viruses continually evolve, vaccine formulations are updated regularly.
WHO monitors these changes and, based on risk assessments, provides vaccine composition recommendations twice yearly through the Global Influenza Surveillance and Response System (GISRS), a longstanding international collaboration with public health experts worldwide, Dr. Zhang said.
The latest vaccines produced for the Northern Hemisphere season do not yet include this new variant, she noted. Nevertheless, early evidence suggests that the existing seasonal vaccines still offer protection against severe disease and reduce the likelihood of hospital admission.
Annually, seasonal influenza affects roughly one billion people globally, with up to five million experiencing severe respiratory illness. Each year, seasonal influenza-related respiratory disease can lead to as many as 650,000 deaths.
Risk-reduction guidance
Vaccination remains the most effective defense, especially for high-risk groups and those who care for them, Dr. Zhang stressed. A preliminary UK-based estimate of vaccine effectiveness against the new variant is promising: about 75% protection against severe disease and hospitalization in children, and around 35% protection among adults.
She cautioned that the upcoming holiday season could drive a further rise in respiratory illnesses. Therefore, proactive planning and preparedness are strongly advised, including boosting vaccination uptake and strengthening health system readiness.
Countries should enhance laboratory diagnostics and continuous, year‑round disease surveillance, while participating in the GISRS network.
Global surveillance remains essential
GISRS comprises influenza centers in 130 countries and about a dozen reference laboratories. When asked about the United States potentially leaving WHO on January 22, 2026, and whether it will stay in GISRS, Dr. Zhang emphasized that, from a flu and respiratory surveillance standpoint, broad international participation is crucial because it is impossible to predict where or when the next pandemic strain will emerge. The interval between a new strain’s appearance, its detection and characterization, and its incorporation into vaccines can profoundly influence lives saved.
In short, vigilance, vaccination, and global collaboration are our best strategies to curb the impact of evolving influenza threats.
