Influenza and other respiratory viruses are on the rise, Dr. Wenqing Zhang, head of the Global Respiratory Threats Unit at the World Health Organization’s (WHO) Epidemic and Pandemic Threat Management Department, told reporters in Geneva, and this year is marked by “the emergence and rapid spread of a new subclass of the AH3N2 virus.”
The new variant, called J.2.4.1 or subclade K, was first detected in August in Australia and New Zealand and has since been detected in more than 30 countries, he said.
DNA shape changer
“Current epidemiological data do not indicate an increase in the severity of the disease, although this genetic change causes a notable evolution in the virus,” said Dr. Zhang.
Flu viruses are constantly evolving, he explained, so the composition of the flu vaccine is updated periodically.
“WHO tracks these changes, assesses associated public health risks, and makes recommendations on vaccine composition twice a year, through a long-standing global system: the Global Influenza Surveillance and Response System (GISRS), in collaboration with other global experts,” Dr. Zhang said.
The new variant (has not been incorporated?) is not part of the composition of the latest vaccines produced for the northern hemisphere influenza season, explained the WHO expert.
Still, “early evidence suggests that current seasonal vaccines continue to offer protection against serious illness and reduce the risk of hospitalization,” he said.
The WHO estimates that around one billion cases of seasonal flu occur each year, including up to five million cases of severe respiratory illnesses. Up to 650,000 deaths each year are due to respiratory illnesses related to seasonal flu.
Tips for risk reduction
“Vaccination remains our most effective defense, even against derived strains, especially for high-risk populations and those who care for them,” Dr. Zhang insisted.
The WHO expert shared the results of an initial estimate of the vaccine’s effectiveness against the new variant, published in the United Kingdom a few weeks ago.
“It’s quite promising,” he said, pointing to data showing the vaccine is about 75 percent effective against severe disease and hospitalization in children and about 35 percent effective among adults.
Dr. Zhang warned that the upcoming holiday season may bring a new surge in respiratory illnesses. “Advanced planning and preparedness efforts, including encouraging vaccination and strengthening health system preparedness, are strongly recommended,” he said.
The WHO expert advised countries to strengthen laboratory diagnostics and year-round disease surveillance and to participate in the WHO GISRS surveillance network.
Global surveillance remains key
The network comprises influenza centers in 130 countries, as well as a dozen reference laboratories.
Asked whether the United States will remain a member of the network next year despite the country’s decision to leave the WHO, effective Jan. 22, 2026, Dr. Zhang said that “from a flu perspective, from a respiratory surveillance and preparedness perspective, we would certainly need every country in the world to participate in surveillance, preparedness and response to flu and other respiratory viruses because we don’t know what the next pandemic strain will be, or when or where it will emerge.”
“And that time between the appearance and the collection, characterization and application of the vaccines… would make a big difference with respect to the number of lives that could be saved,” he concluded.
