Global Respiratory Virus Activity: Weekly Update N° 574

Overview

Globally, influenza positivity remained below 10% in week 15 2026. SARS-CoV-2 activity remained low overall. Influenza predominated and positivity was around 10% in the northern hemisphere temperate and subtropical areas and in tropical areas. In the southern hemisphere temperate and subtropical areas, influenza and SARS-CoV-2 positivity were both low. Globally, RSV positivity remained stable and low.

Influenza

Globally, influenza detections remained low in week 15 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, Eastern Europe, and Southern and Eastern Asia, and in single countries in South West Europe and Western and Eastern Africa. Percent positivity was over 30% in single countries in Central America and the Caribbean and Eastern Europe. Small increases in activity were observed in single countries in South West and Eastern Europe, and Western and Southern Asia.

In the southern hemisphere, influenza activity remained low overall although elevated positivity (>10%) was reported in single countries in Temperate and Tropical South America, Southern Africa and South-East Asia. Small increases in activity were observed in a few countries in Temperate South America.

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

SARS-CoV-2

Globally, SARS-CoV-2 positivity remained stable and low across reporting countries, with a single country reporting elevated activity (>10%) in Western Asia. Small increases were observed in single countries in Western Africa and Western Asia.

Respiratory Syncytial Virus (RSV)

Globally, RSV positivity remained stable and low with elevated positivity (>10%) reported in a few countries in Tropical South America and Europe, and in single countries in Northern Africa and Western and Central Asia. Percent positivity was over 30% in a single country in Eastern Africa. A Small increase in activity was reported in a single country in Northern Europe. RSV and influenza activity were both elevated in a few countries in Europe.

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 (25), low (8) and moderate (2); transmissibility using syndromic data was reported as below seasonal threshold (29) and low in a single country. 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.