Islamabad: A new strain of the flu virus, known as H3N2 subclade K, is spreading faster than expected across the world, the World Health Organization warned on Thursday, though experts say it is not more dangerous than earlier versions. Scientists first detected its rise in Australia and New Zealand a few months ago, and it has since appeared in more than thirty countries.
The virus has developed small genetic changes that help it move through communities more quickly, which is why several regions are seeing earlier than usual flu seasons.
Despite these changes, health agencies say the current flu vaccine is still doing its main job: protecting people from severe illness and hospital visits. Early data show strong protection for children and good protection for adults. Doctors continue to stress that vaccination is the best shield for older people, pregnant women and those with chronic illnesses as this fast-moving strain spreads.
WHO says seasonal influenza is rising across the world earlier than expected this winter, driven largely by the rapid growth of the H3N2 subclade K. The surge coincides with the onset of winter in the northern hemisphere and a wider increase in respiratory infections. Global activity remains within seasonal limits but several regions are reporting earlier and higher transmission. The new subclade has already been detected in more than 34 countries and marks a significant shift in the circulating virus, although there is still no evidence of increased severity.
Pakistan is also witnessing increased circulation of Influenza A viruses, including H3N2. The National Institute of Health in Islamabad has confirmed H3N2 cases from several cities in recent weeks, while hospitals in major urban centres are reporting more patients with high fever, persistent cough and influenza-related pneumonia. Clinicians say children, older adults and people with weakened immunity appear to be the most affected.
Globally, influenza activity has risen steadily since October. Northern hemisphere countries are reporting early season starts with H3N2 dominating. Southern hemisphere countries have come out of unusually long seasons, while tropical regions continue to show steady transmission and a sharp rise in H3N2 since late September. Influenza A remains the leading virus worldwide.
The rapid expansion of H3N2 subclade K is drawing the most attention. It surged in Australia and New Zealand in August before spreading across Asia, Europe, North America, the Middle East and Africa. South America is the only region where it has not yet gained a foothold. Although the virus has acquired several genetic changes, WHO says there is no indication that it is causing more severe disease.
WHO notes that early global data show the current flu vaccine continues to offer meaningful protection against severe illness and hospital visits, particularly for children, even as its effectiveness against mild disease is still being evaluated. The agency stresses that vaccination remains the strongest defence, especially when circulating viruses show signs of genetic drift.
With influenza, RSV and other respiratory viruses rising at the same time, WHO warns that health systems could come under pressure in the months ahead. Countries have been urged to strengthen surveillance, expand testing and ensure timely use of antivirals for high-risk patients. Hospitals have been advised to reinforce infection-control measures, including screening, patient isolation where necessary and consistent mask use for staff caring for suspected or confirmed cases. People who fall ill are encouraged to stay home, practise hand hygiene and use masks while symptomatic.
WHO has not recommended any travel or trade restrictions based on the current situation.
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