Global Respiratory Virus Activity: Weekly Update N° 590

Overview

In week 31 2026, influenza positivity was below 10% and SARS-CoV-2 activity remained low globally. During the past few weeks, influenza positivity increased but remained below 10% overall in the northern hemisphere temperate and subtropical areas. RSV positivity also remained low globally.

Influenza

Globally, influenza detections remained low in week 31 with influenza A and B viruses detected in similar proportions.

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, Eastern and Southern Africa and Oceania. Small increases in activity were observed in single countries in Eastern Africa and Oceania.

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

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

SARS-CoV-2

Globally, SARS-CoV-2 positivity remained stable and low across most reporting countries, with elevated positivity (>10%) reported in countries in Central America and the Caribbean and Tropical South America and in single countries in Northern Europe and Western Asia. Small increases in activity were observed in two countries in South West Europe and in single countries in Central America and the Caribbean, Tropical South America and Western Africa.

Respiratory Syncytial Virus (RSV)

RSV positivity was elevated (>10%) in a few countries in Central America and the Caribbean, Tropical and Temperate South America and in a single country in Western, Eastern and Southern Africa. Percent positivity was over 30% in single countries in Central America and the Caribbean and Temperate South America. Small increases in activity were observed in single countries in Central America and the Caribbean and Temperate South America. RSV and influenza activity were both elevated in a few countries in Central America and the Caribbean, Temperate South America, Western and Southern Africa.

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 (1) and low (1); transmissibility using syndromic data was reported as low (1). In the northern hemisphere temperate and subtropical areas, influenza-specific transmissibility was reported as below seasonal threshold (13) and low (1); transmissibility using syndromic data was reported as below seasonal threshold (10). Influenza-specific transmissibility was reported as low in one 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.