Global Respiratory Virus Activity: Weekly Update N° 598

Overview

In week 39 2026, globally, influenza positivity was below 10% and SARS-CoV-2 positivity remained stable and low. Influenza positivity was below 10% in the southern hemisphere temperate and subtropical areas and at 10% in the tropical areas. Influenza positivity was below 10% in the northern hemisphere temperate and subtropical areas with a decrease in the reported specimens tested in the most recent week. RSV positivity also remained low globally.

Influenza

Globally, influenza detections remained low in week 39 with influenza A virus detections predominant. An increase in the proportion of influenza A(H1N1)pdm09 detections has been observed over recent weeks.

In the southern hemisphere, influenza percent positivity was elevated (>10%) in single countries in Tropical and Temperate South America and Eastern Africa. Percent positivity was over 30% in single countries in South-East Asia and Oceania. Increases in activity were reported in single countries in Temperate South America and South-East Asia.

In the northern hemisphere, influenza percent positivity was elevated (>10%) in some countries in Western Africa, Southern, South-East and Eastern Asia and in a single country in Central America and the Caribbean and Western Asia. Percent positivity was over 30% in some countries in Western, Southern and South-East Asia and in single countries in Central America and the Caribbean and Western Africa. Increases in activity were observed in some countries in Western and South-East Asia and in single countries in Central America and the Caribbean, Western Africa and Southern Asia.

In the zones with elevated positivity, influenza A(H3N2) was predominant in Eastern Asia; influenza A(H1N1)pdm09 was predominant in Western, Southern and South-East Asia and influenza B was predominant in Tropical and Temperate South America. Influenza A and B were codominant in Central America and the Caribbean and Western Africa and influenza A(H3N2) and influenza A(H1N1)pdm09 were codominant in Oceania.

SARS-CoV-2

Globally, SARS-CoV-2 positivity remained stable and low across most reporting countries, with elevated positivity (>10%) reported in some countries in Central America and the Caribbean and Eastern Asia, and in single countries in South West and Northern Europe and South-East Asia. A medium increase in activity was observed in a single country in Central America and the Caribbean, and small increases in activity were observed in single countries in South West and Eastern Europe.

Respiratory Syncytial Virus (RSV)

RSV positivity was elevated (>10%) in a few countries in Central America and the Caribbean and Temperate South America and in a single country in Tropical South America. Percent positivity was over 30% in a single country in Southern Asia. A small increase in activity was observed in a single

country in Central America and the Caribbean. RSV and influenza activity were both elevated in countries in Temperate South America and Southern Asia.

Severity assessment

The severity assessments here are reported from countries, areas and territories. Assessments for transmissibility can be reported based on syndromic parameters and/or influenza-specific parameters. In the southern hemisphere temperate and subtropical areas, influenza-specific transmissibility was reported as below seasonal threshold in a single country and low in a single country; transmissibility using syndromic data was reported as below seasonal threshold in a single country. In the northern hemisphere temperate and subtropical areas, influenza-specific transmissibility was reported as below seasonal threshold in 13 countries, low in a single country and moderate in a single country; transmissibility using syndromic data was reported as below seasonal threshold in eight countries and low in a single country. Influenza-specific transmissibility was reported as below seasonal threshold in a single country in the tropical areas. 

WHO encourages countries, especially those that have received the multiplex influenza and SARS-CoV-2 reagent kits from GISRS, to conduct integrated surveillance of influenza and SARS-CoV-2 and report epidemiological and laboratory information in a timely manner to established regional and global platforms. The guidance can be found here.

Starting with report #501, the Global Respiratory Virus Activity Weekly Update included data from sentinel surveillance and other types of systematically conducted virologic surveillance. Countries, areas, and territories use a variety of approaches to monitor respiratory virus activity and data in this report may vary from surveillance reports posted elsewhere. Analyses stratified by source of surveillance is available through Respimart.