Global Respiratory Virus Activity: Weekly Update N° 599

Overview

Influenza

In week 40 2026, globally, influenza positivity was below 10% and SARS-CoV-2 positivity remained stable and low. Influenza positivity was below 10% in the northern hemisphere temperate and subtropical areas with a decrease in the reported  specimens tested in the last two weeks. Influenza positivity was below 10% in the southern hemisphere temperate and subtropical areas and at 10% in the tropical areas. RSV positivity also remained low globally.

Globally, influenza detections remained low in week 40 with influenza A virus detections predominant.

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

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

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

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, South West and Northern Europe, and in single countries in Northern Africa, South-East and Eastern Asia. Increases in activity were observed in two countries in South West Europe and in single countries in Northern and Eastern Africa and Western Asia.

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 single countries in Western Africa and Southern Asia. Small increases in activity were observed in single countries in Central America and the Caribbean and Tropical South America. RSV and influenza activity were both elevated in countries in Central America and the Caribbean, Temperate South America, Western Africa 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 northern hemisphere temperate and subtropical areas, influenza-specific transmissibility was reported as below seasonal threshold in 15 countries, low in a single country and moderate in a single country; transmissibility using syndromic data was reported as below seasonal threshold in nine countries and low in two countries. 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. 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.