As India Battles H1N1, WHO Sounds H5N1 Alert Across Asia-Pacific

Just as India is gearing up to tackle a seasonal influenza wave, with H1N1 or swine flu cases drawing attention, the World Health Organisation (WHO) has sounded a fresh warning on another influenza threat — highly pathogenic avian influenza A (H5N1).

The warning comes amid a spurt in outbreaks of H5N1 among birds in countries across the Asia-Pacific region, raising concerns over the possibility of the virus spilling over from animals to humans.

The WHO has now urged countries to strengthen surveillance and ensure their health systems are ready to detect and respond rapidly to any human infections.

The message came after more than 150 influenza experts, laboratory scientists and public-health officials met virtually from August 25 to 27 for the 19th Biregional Meeting of National Influenza Centres and Influenza Surveillance, jointly organised by WHO’s South-East Asia and Western Pacific regional offices.

The timing is significant for India, which is already monitoring seasonal influenza. The National Centre for Disease Control (NCDC) maintains dedicated surveillance and technical guidance for seasonal influenza, including H1N1, and its latest update was issued on August 11.

But H5N1 is a different threat. While seasonal influenza viruses such as H1N1 circulate primarily among humans, H5N1 is an avian influenza virus that primarily affects birds and can occasionally infect humans, particularly following exposure to infected animals or contaminated environments. WHO says zoonotic influenza viruses can cause illness ranging from mild flu-like symptoms to severe respiratory disease and death.

The latest WHO meeting placed particular emphasis on the spread of highly pathogenic H5N1 in birds in the Pacific and recent incursions reported in Australia and New Zealand.

WHO stressed that the response cannot be left to the health sector alone. Animal health, human health and environmental authorities need to work together under the One Health approach to detect potential spillovers early and contain them before they become a wider public-health threat.

“Australia and New Zealand’s recent experience is a sharp reminder that vigilance cannot lapse,” said Dr Saia Ma’u Piukala, WHO Regional Director for the Western Pacific, stressing the importance of coordination between human, animal and environmental health authorities.

WHO, along with the Food and Agriculture Organisation, UN Environment Programme, World Organisation for Animal Health and Pacific Community, has also undertaken a Rapid Joint One Health Risk Assessment to assess the risk of H5N1 entering Pacific Island countries and identify preparedness measures.

For India, the warning is relevant because influenza surveillance cannot operate in isolation from developments in animal populations. Early detection depends on being able to identify unusual infections, characterise viruses and share information rapidly between human and animal health systems.

India showcased its own surveillance experience at the WHO meeting, highlighting the integration of influenza surveillance into the Integrated Health Information Platform. The system provides near-real-time data for analysing influenza trends and supporting faster outbreak detection and response.

The WHO's latest global respiratory-virus update also shows that influenza activity is not uniformly high worldwide. However, elevated influenza positivity has been reported in parts of South and South-East Asia and several other regions, reinforcing the need for continued surveillance.

The distinction between H1N1 and H5N1 is therefore important. A rise in seasonal H1N1 does not mean H5N1 is spreading among people. WHO continues to describe avian influenza viruses as distinct from seasonal human influenza viruses, with human transmission remaining an important point of surveillance rather than something to assume from animal outbreaks alone.

The WHO meeting repeatedly returned to one message: collecting data is not enough unless it leads to timely action.

“Surveillance data only matter when they change what public health systems do,” said Dr Gina Samaan, WHO Regional Emergency Director for the Western Pacific.

The region is consequently being urged to strengthen laboratory capacity, genomic sequencing, timely sharing of influenza viruses and data, and the ability to rapidly characterise unusual strains.

The broader concern is preparedness. H5N1 has been causing unprecedented levels of disease and deaths among wild birds and poultry in several parts of the world since the emergence of the H5 clade 2.3.4.4b viruses in 2020. Human infections remain rare, but when they occur, they can be severe.

For India, the immediate public-health priority remains keeping a close watch on seasonal influenza and ensuring appropriate diagnosis and treatment. But the WHO alert is also a reminder that influenza preparedness cannot stop at human hospitals.

“Our strength is in our network – in sharing expertise, information and capacities, and in supporting one another to be better prepared for the threats ahead,” said Dr Nilesh Buddha, Officer-in-Charge for the WHO Regional Office for South-East Asia. “Where expertise exists in one country, we should facilitate its transfer and application across the region; where specialised capacities are available, we should strengthen pathways for countries to access them.”

Dr Buddha also stressed the importance of coordinated investments, resource mobilisation and strategic prioritisation at a time when resources are increasingly constrained. He called for greater collaboration to make optimal use of existing capacities, maximise impact and avoid duplication.

From 2003 to August 2025, the WHO has reported 990 human H5N1 cases across 25 countries, including 475 deaths – a 48% fatality rate.

In humans, H5N1 infection can resemble a severe bout of influenza, with symptoms such as high fever, cough, sore throat and muscle aches, while some infected people may remain symptom-free. Although the risk to the general population remains low, health authorities are closely monitoring the virus for any changes that could increase its ability to spread among humans, according to reports.