Influenza and other respiratory viruses are surging, Dr. Wenqing Zhang, head of the global respiratory threats unit at the World Health Organization’s (WHO) Department of Epidemic and Pandemic Threat Management, told reporters in Geneva. This year is marked by “the emergence and rapid expansion of a new subclade of the AH3N2 virus”.
The new variant – called J.2.4.1 or subclade K – was first seen in August in Australia and New Zealand and has since been detected in more than 30 countries, she said.
DNA shape changer
“Current epidemiological data do not indicate an increase in disease severity, although this genetic change is leading to notable evolution of the virus,” Dr. Zhang said.
Flu viruses are constantly evolving, she explained, which is why the composition of the flu vaccine is regularly updated.
“WHO monitors these changes, assesses the 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,” said Dr Zhang.
The new variant (has not been integrated?) is not part of the composition of the latest vaccines produced for the Northern Hemisphere flu season, explained the WHO expert.
Still, “early evidence suggests that current seasonal vaccines continue to provide protection against severe disease and reduce the risk of hospitalization,” she said.
The WHO estimates that there are around one billion cases of seasonal flu each year, including up to five million cases of severe respiratory illness. Each year, up to 650,000 deaths are caused by respiratory illnesses linked to seasonal flu.
Risk reduction advice
“Vaccination remains our most effective defense, including against derived strains, particularly for high-risk populations and those who care for them,” insisted Dr. Zhang.
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 pretty promising,” she said, pointing to data that shows the vaccine is about 75 percent effective against severe illness and hospitalizations in children and about 35 percent effective in adults.
Dr Zhang warned that the upcoming holiday season could bring a further rise in respiratory illnesses. “Advanced planning and preparedness efforts, including encouraging the uptake of vaccination and strengthening health system preparedness, are strongly recommended,” she said.
The WHO expert advised countries to strengthen laboratory diagnostics and disease surveillance throughout the year and participate in the WHO GISRS surveillance network.
Global surveillance remains essential
The network includes influenza centers in 130 countries as well as a dozen reference laboratories.
Asked whether the United States would remain a member of the network next year despite the country’s decision to leave the WHO, effective January 22, 2026, Dr. Zhang responded that “from an influenza perspective, from a respiratory surveillance and preparedness perspective, we would certainly need all countries in the world to participate in surveillance, preparedness and response to influenza and other respiratory viruses, because we don’t know the next strain pandemic, when and where it will appear.
“And that time between emergence and detection, characterization and rollout of vaccines… that would make a big difference in terms of how many lives could be saved,” she concluded.
