Influenza A(H1N1)pdm09 has emerged as the predominant influenza strain detected in India, accounting for 75% of influenza-positive samples, according to the latest World Health Organization (WHO) surveillance data covering September 1–14, 2026. The data, updated on September 21, highlights the continued circulation of seasonal influenza across India and the wider WHO South-East Asia Region.

According to the surveillance data for WHO epidemiological weeks 36 and 37, a total of 817 out of 3,632 samples tested across the South-East Asia Region were positive for influenza, representing an overall positivity rate of approximately 22%. In India, A(H1N1)pdm09 accounted for three out of every four influenza-positive samples, significantly higher than the 50% regional proportion. H1N1 was also predominant in Bhutan and Thailand, accounting for 97% and 74% of positive influenza samples, respectively.

The latest WHO findings come amid continued monitoring of seasonal influenza activity in India. The Union Ministry of Health and Family Welfare, along with ICMR and NCDC, has stated that the current H1N1 activity reflects expected seasonal changes, with no new or unusual influenza virus strain detected. ICMR has also reported that the circulating A(H1N1)pdm09 virus belongs to a lineage already in circulation.

Healthcare experts have noted that while seasonal H1N1 infections are generally self-limiting, older adults, young children, pregnant women and people with underlying health conditions can face a higher risk of complications. Preventive measures include respiratory hygiene, appropriate medical consultation and timely treatment for patients at higher risk.

Globally, WHO reported that influenza positivity stood at 10% in epidemiological week 37, with influenza A remaining predominant. In South-East Asia and other regions with elevated activity, A(H1N1)pdm09 continues to be among the dominant circulating influenza viruses.