Global Respiratory Virus Activity: Weekly Update N° 596

Overview

In week 37 2026, globally, influenza positivity was at 10% and SARS-CoV-2 positivity remained stable and low. Influenza positivity was under 10% in the southern hemisphere temperate and subtropical areas and just above 10% in the tropical areas. Influenza positivity increased to just above 10% in the northern hemisphere temperate and subtropical areas but there was also a decrease in the reported specimens tested for week 37. RSV positivity remained low globally.

Influenza

Globally, influenza detections remained low in week 37 with influenza A virus detections predominant.

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

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

In the zones with elevated positivity, influenza A(H3N2) was predominant in Western Africa, Eastern Asia and Oceania; influenza A(H1N1)pdm09 was predominant in Eastern Africa, 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.

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, Northern and South West Europe and Eastern Asia, and in a single country in Tropical South America. Small increases in activity were observed in some countries in Northern Europe and in single countries in Central America and the Caribbean and 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 Western Africa. Percent positivity was over 30% in single countries in Temperate South America and Southern Asia. Increases in activity were observed in single countries in Eastern Africa and Southern Asia. 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 low in two countries; 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 seven countries. 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.