WHO Says Global Influenza Activity Remains Relatively Low

Global influenza activity remains relatively low, according to the latest World Health Organization surveillance data, although several regions are recording increases as countries move through different stages of their seasonal influenza cycles.

For epidemiological week 37, ending September 13, WHO reported global influenza positivity at about 10%. Influenza A viruses remained predominant, while respiratory syncytial virus, or RSV, and SARS-CoV-2 activity remained relatively low globally.

The figures provide a broad picture of influenza circulation but do not mean that influenza activity is low in every country.

Global influenza positivity remains around 10%

WHO’s latest global respiratory-virus update found influenza positivity at approximately 10% during week 37.

Positivity was below 10% in temperate and subtropical areas of the Southern Hemisphere and just above 10% in tropical areas. Activity also increased to just above 10% in temperate and subtropical areas of the Northern Hemisphere.

WHO cautioned that fewer specimens were reported during week 37, which can affect interpretation of the trend.

The global figure should therefore be understood as a surveillance indicator rather than a direct measure of the number of people infected with influenza.

Influenza A remains predominant

Influenza A viruses accounted for most of the influenza detections reported globally during the latest surveillance period.

The predominance of influenza A does not by itself indicate that the current season will be more or less severe than previous seasons.

WHO’s surveillance system tracks the viruses circulating in different populations so that changes can be detected and vaccine recommendations can be adjusted when necessary.

The virus mix can also vary considerably between countries and regions.

Regional differences are becoming more visible

Although global activity remains relatively low, WHO reported elevated influenza positivity in several parts of the world.

In the Southern Hemisphere, positivity was above 10% in some countries in temperate South America and in individual countries in tropical South America and Eastern and Southern Africa.

The picture is different in the Western Pacific.

WHO’s regional surveillance bulletin for week 37 found that influenza positivity in the region increased from 14% in week 35 to 16% in week 37. Activity increased in all transmission zones except Oceania, Melanesia and Polynesia.

This demonstrates why global averages can conceal significant local or regional increases.

Asia is seeing increases in several areas

WHO’s Western Pacific surveillance showed continued increases in influenza activity across Eastern Asia.

Activity increased in all countries and areas in the Eastern Asia transmission zone except Mongolia, where WHO reported zero influenza positivity since May 2026.

In South-East Asia, activity increased in most countries, although Malaysia, the Philippines and Vietnam did not follow the same pattern during the reporting period.

The regional differences reflect the fact that influenza seasons do not begin and end simultaneously across the world.

H3N2 is prominent in the Western Pacific

The latest Western Pacific data also show differences in the influenza viruses circulating in the region.

Influenza A(H3) accounted for 48.4% of detections, followed by influenza A(H1N1)pdm09 at 26.7% and influenza B/Victoria at 23.8%.

These figures describe the distribution of detected influenza viruses in the surveillance system.

They should not be interpreted as representing the proportion of all influenza infections in the population because surveillance samples are not a complete census of infections.

Influenza activity had been rising before the latest update

WHO’s earlier weekly updates show that the current global picture has evolved over several months.

In week 35, ending August 30, global influenza positivity remained below 10%, with influenza A detections predominant. Some countries in South America, South-East Asia and Oceania had considerably higher positivity.

By week 36, ending September 6, global positivity had reached around 10%, while influenza activity remained relatively low overall.

The week 37 update therefore represents continued relatively low global activity alongside increases in specific regions.

Seasonal patterns matter

Influenza activity naturally changes according to season, geography and population.

The Southern Hemisphere experiences its main seasonal influenza period during a different part of the year from the Northern Hemisphere.

Tropical countries can experience influenza circulation throughout the year, with the timing and intensity of peaks varying between locations.

For that reason, an increase in one region does not necessarily mean that global influenza activity is undergoing a simultaneous increase.

WHO monitors these differences through its Global Influenza Surveillance and Response System, known as GISRS. The system uses data shared by countries and regional surveillance networks to track circulating respiratory viruses.

Africa has areas of elevated activity

Africa is included in the regional picture showing uneven influenza circulation.

WHO’s latest global update identified individual countries in Eastern and Southern Africa with influenza positivity above 10%.

Earlier WHO updates had also identified elevated activity in individual African countries.

The data do not support describing the whole African continent as experiencing a single influenza trend because surveillance results differ substantially between countries.

This distinction is particularly important for countries such as Nigeria, where local surveillance data would be needed to assess the situation nationally.

SARS-CoV-2 remains low globally

The WHO update also tracks SARS-CoV-2 alongside influenza and RSV.

SARS-CoV-2 positivity remained stable and low globally during week 37.

This does not mean COVID-19 transmission has stopped.

Rather, the surveillance data indicate that the proportion of tested respiratory specimens positive for SARS-CoV-2 remained relatively low in the reporting system during the period covered.

WHO continues to monitor SARS-CoV-2 because the virus remains in circulation and can continue to produce infections and outbreaks.

RSV activity also remains low globally

Respiratory syncytial virus, or RSV, was another virus included in WHO’s surveillance.

RSV positivity remained low globally during week 37.

Like influenza, RSV can show substantial seasonal and geographic differences.

The global figure therefore should not be interpreted as meaning that RSV activity is absent in individual communities.

Surveillance data have limitations

WHO’s respiratory-virus reports depend on samples submitted through national and regional surveillance systems.

Changes in the number of specimens tested can affect reported positivity.

The week 37 global report specifically noted a decrease in the number of specimens tested, which means comparisons with earlier weeks need to be interpreted carefully.

Surveillance data also do not directly measure every infection occurring in the population.

People with mild illness may never seek medical attention or be tested, while testing strategies differ between countries.

Consequently, reported positivity is most useful for monitoring trends and identifying areas where activity is changing.

Influenza surveillance also supports vaccine decisions

Monitoring which influenza viruses are circulating has a direct role in vaccine policy.

WHO holds regular consultations to review global influenza activity and recommend the composition of seasonal influenza vaccines.

On September 25, WHO held an information meeting on the composition of influenza vaccines for the 2027 Southern Hemisphere influenza season. The meeting included discussion of global virus activity, virus characterisation and recommended vaccine composition.

The process illustrates how surveillance information is used to prepare for future influenza seasons.

Zoonotic influenza remains under monitoring

Seasonal influenza is not the only influenza-related issue monitored by WHO.

The organisation also tracks influenza viruses that circulate in animals and can occasionally infect humans.

WHO’s Weekly Epidemiological Record reported that between August 8 and September 6, 2026, one human H5N1 infection, three H9N2 infections and two H1N2 variant infections were officially reported.

WHO reported no sustained human-to-human transmission associated with those infections during the assessment period.

These infections are monitored separately from ordinary seasonal influenza because some animal influenza viruses have pandemic potential.

What the current data mean for the public

The latest global figures do not indicate a worldwide influenza surge.

At the same time, the regional increases show why continued surveillance is necessary.

Influenza activity can rise rapidly in particular countries as seasonal transmission increases, and global averages can change as different regions enter their respective influenza seasons.

The WHO data therefore support a more nuanced picture: relatively low global activity, but increasing activity in some regions and individual countries.

What happens next

WHO will continue receiving surveillance data from national influenza centres and other participating laboratories through GISRS.

The organisation’s regular updates will track whether the regional increases continue, level off or spread to additional areas.

Vaccine composition decisions will also continue to depend on the viruses detected and characterised through international surveillance.

For governments, the continuing priority is maintaining surveillance and ensuring that health systems can respond if activity rises.

Global activity remains relatively low, but monitoring continues

As of September 27, 2026, WHO’s latest global data show influenza activity remaining relatively low overall, with global positivity around 10% in week 37.

However, this broad picture masks meaningful regional differences. Influenza activity is increasing in parts of Asia and has remained elevated in some countries in Africa, South America and other regions.

The available evidence therefore does not support describing the current situation as a global influenza outbreak or surge.

Instead, the latest surveillance points to relatively low global activity accompanied by regional increases that WHO continues to monitor.