Global Respiratory Virus Activity: Weekly Update N° 580

Overview

In week 21 2026, influenza positivity remained below 10% and SARS-CoV-2 activity remained low globally. Influenza positivity was around 10% in the tropical areas. RSV positivity also remained stable and low globally. Please be aware that due to a transition of the data management system, data reporting is paused for three consecutive weeks (weeks 21 to 23) in the European region. Incomplete reporting for week 21 from other regions may complicate interpretation of trends.

Influenza

Globally, influenza detections remained low in week 21 and influenza B viruses were predominant among influenza detections.

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 South-East Asia. A small increase in activity was observed in a single country in South-East Asia.

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

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

SARS-CoV-2

Globally, SARS-CoV-2 positivity remained stable and low across reporting countries, with elevated positivity (>10%) reported in single countries in Western and South-East Asia. There were no countries reporting increases in activity in week 21.

Respiratory Syncytial Virus (RSV)

Globally, RSV positivity remained stable and low, with elevated positivity (>10%) reported in a few countries in Central America and the Caribbean and Tropical South America. Percent positivity was over 30% in single country in Eastern Africa and Southern Asia. Increases in activity were observed in a single country in Central America and the Caribbean. RSV and influenza activity were both elevated in countries in Central America and the Caribbean, Eastern 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 low (1); transmissibility using syndromic data was reported as below seasonal threshold (1). Influenza-specific transmissibility was reported as low in a single country in the southern hemisphere temperate and subtropical areas and below seasonal threshold in two countries 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.