Global Respiratory Virus Activity: Weekly Update N° 583

Overview

In week 24 2026, influenza positivity remained below 10% and SARS-CoV-2 activity remained low globally. Influenza positivity was around 10% in the southern hemisphere temperate and subtropical areas. RSV positivity also remained low globally. Please be aware that due to a transition of the data management system, data reporting is paused for four consecutive weeks (weeks 21 to 24) in the European region.

Influenza

Globally, influenza detections remained low in week 24 and influenza B viruses were predominant among influenza detections.

In the northern hemisphere, influenza percent positivity was elevated (>10%) in some countries in Central America and the Caribbean and Southern Asia and in single countries in Northern and Eastern Africa, Western, South-East and Eastern Asia. No increases in activity were observed in the northern hemisphere.

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

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

SARS-CoV-2

Globally, SARS-CoV-2 positivity remained stable and low across reporting countries, with elevated positivity (>10%) reported in some countries in Central America and the Caribbean and Tropical South America and in single countries in Middle Africa, Western and South-East Asia. Increases in activity were reported in two countries in Tropical South America and in single countries in Central America and the Caribbean, Middle and Eastern Africa, Southern and South-East Asia.

Respiratory Syncytial Virus (RSV)

RSV positivity was elevated (>10%) in a few countries in Central America and the Caribbean and Tropical South America and in single countries in Eastern Africa and Oceania. Percent positivity was over 30% in single countries in Tropical South America and 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 single 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. Influenza-specific transmissibility was reported as moderate (1) and high (1) in the southern hemisphere temperate and subtropical areas and below seasonal thresholds in a single country in the tropics. Transmissibility using syndromic data was reported as low in a single country in the southern hemisphere temperate and subtropical areas. In the northern hemisphere temperate and subtropical areas, influenza-specific transmissibility was reported as low in a single country and transmissibility using syndromic data was reported as below seasonal thresholds in a single country. 

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.