Islamabad: Pakistan has detected the fast spreading subclade K of Influenza A (H3N2), dubbed the “super flu” in several Western countries, with the National Institute of Health issuing an urgent nationwide advisory after laboratory surveillance showed that around 20 percent of H3N2 samples circulating in the country belong to this genetically drifted variant, which has been linked with more severe illness and rapid transmission.
In its advisory issued on Monday, the NIH warned federal and provincial health authorities that the country is already witnessing an unusual early surge in seasonal influenza, driven largely by H3N2, and that hospitals should prepare for a further rise in outpatient visits and admissions over the coming weeks.
The alert has been issued ahead of the expected peak flu season to prevent health facilities from being overwhelmed and to reduce avoidable complications and deaths.
According to the NIH, subclade K of Influenza A (H3N2) has emerged globally during the ongoing 2025–26 flu season, with a sharp increase in detections reported since August across multiple World Health Organization regions.
The South East Asia region, including Pakistan, has seen H3N2 become the dominant influenza A subtype, accounting for about 66 percent of all influenza A cases detected since May 2025. Similar trends have been documented in Australia and New Zealand, where a significant proportion of influenza cases are now linked to this subclade.
The advisory states that Pakistan is recording a steady increase in influenza like illness and severe acute respiratory infection cases. Between epidemiological weeks 44 and 49, health authorities reported more than 340,000 suspected influenza like illness cases from all provinces and regions through the Integrated Disease Surveillance and Response system.
Laboratory data show that around 12 percent of tested samples were positive for H3N2, with officials cautioning that the proportion may rise as winter intensifies and indoor crowding increases.
NIH officials have warned that while seasonal influenza is often perceived as mild, H3N2 is historically associated with more severe disease, particularly among older adults, young children, pregnant women, people with obesity and those living with chronic conditions such as diabetes, heart disease and respiratory illnesses.
The virus spreads mainly through respiratory droplets and close contact, making congested urban settings and poorly ventilated spaces particularly vulnerable to rapid transmission.
The advisory urges all health departments to strengthen surveillance for influenza like illness and severe acute respiratory infections, ensure timely reporting of suspected cases and strictly enforce infection prevention and control measures in hospitals and clinics. It also calls for improved risk communication to counter misinformation surrounding the “super flu” label and to encourage early care seeking among high risk groups.
Emphasising prevention, the NIH has reiterated that seasonal influenza vaccination remains the most effective tool to reduce severe disease and deaths. It noted that despite genetic changes in circulating viruses, current WHO recommended vaccines for the Northern Hemisphere continue to offer protection against serious outcomes, including from H3N2 subclade K.
The recommended vaccine for the 2025–26 season includes protection against H3N2 like viruses, H1N1 and influenza B strains.
The advisory also outlines clinical management guidance, advising early antiviral treatment with oseltamivir for hospitalized patients and individuals at high risk of complications, including children under two years of age, adults aged 65 years and above, pregnant and postpartum women and immunocompromised patients.
While most influenza infections are self limiting, delayed treatment in vulnerable populations can lead to severe pneumonia, respiratory failure and death.
The NIH has directed provincial and district authorities to widely circulate the advisory, ensure readiness of health facilities and maintain close coordination with surveillance and laboratory networks. Officials stressed that public awareness, vaccination and prompt medical attention are critical to limiting the impact of the rapidly spreading H3N2 subclade as the flu season gathers pace.
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