WHO Warns of Rapid Spread of New Influenza Variant
The World Health Organization (WHO) has raised concerns over the rapid spread of a new influenza virus variant, while stressing that vaccination remains the most effective form of protection against severe illness.
Speaking in Geneva on Wednesday, Wenqing Zhang, Unit Head for Global Respiratory Threats at WHO’s Department of Epidemic and Pandemic Threats Management, said the current influenza season has been marked by the emergence and swift expansion of a new AH3N2 virus subclade.
According to Ms. Zhang, the variant—known as J.2.4.1 or subclade K—was first identified in August in Australia and New Zealand and has since been detected in more than 30 countries worldwide.
“Current epidemiological data do not indicate an increase in disease severity, although this genetic shift represents a notable evolution of the virus,” she said.
Ms. Zhang explained that influenza viruses are constantly evolving, which necessitates regular updates to vaccine composition. WHO monitors these changes through its Global Influenza Surveillance and Response System (GISRS), working alongside international experts to assess public health risks and issue vaccine recommendations twice each year.
However, she noted that the newly identified variant was not included in the composition of the most recent vaccines produced for the Northern Hemisphere influenza season.
Despite this, early findings suggest that existing seasonal vaccines continue to provide protection against severe disease and help reduce hospitalisation rates. “Vaccination remains our most effective defence, including against drifted strains, particularly for high-risk populations and their caregivers,” Ms. Zhang said.
WHO estimates that seasonal influenza results in about one billion infections annually, including up to five million cases of severe respiratory illness, and as many as 650,000 deaths each year.
Citing early data from the United Kingdom, Ms. Zhang described preliminary vaccine effectiveness against the new variant as “quite promising.” The findings indicate approximately 75 per cent effectiveness against severe disease and hospitalisation in children, and about 35 per cent effectiveness among adults.
She warned that the upcoming holiday season could lead to a further rise in respiratory infections and urged countries to intensify preparedness measures, including increasing vaccination uptake and strengthening health system readiness.
Ms. Zhang also called on countries to enhance laboratory diagnostics, maintain year-round disease surveillance, and actively participate in the WHO GISRS network, which includes influenza centres in 130 countries and several reference laboratories.
Emphasising the importance of global cooperation, she said every country plays a critical role in influenza surveillance and pandemic preparedness.
“We do not know which strain could cause the next pandemic, or when and where it may emerge,” she said. “The time between detection and vaccine development can make a significant difference in the number of lives saved.”