Global Respiratory Virus Activity: Weekly Update N° 575

Overview

In week 16 2026, influenza positivity remained below 10% and SARS-CoV-2 activity remained low globally and in the northern hemisphere temperate and subtropical areas, tropical areas and the southern hemisphere temperate and subtropical areas. RSV positivity also remained stable and low globally.

Influenza

Globally, influenza detections remained low in week 16 and influenza B viruses were predominant among influenza detections.

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

In the southern hemisphere, influenza activity remained low overall although elevated positivity (>10%) was reported in some countries in Temperate South America and in single countries in Tropical South America, Southern Africa and South-East Asia. A small increase in activity was observed in a single country 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, Eastern Africa and Southern Asia. Influenza A(H1N1)pdm09 and A(H3N2) were codominant in Southern Africa. Influenza B was predominant in Western Africa, and 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. A small increase was observed in a single country in Eastern 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 Northern and Eastern Europe, and in single countries in Northern Africa and Western Asia. Percent positivity was over 30% in some countries in Eastern Africa. Small increases in activity were reported in single countries in Eastern Europe and Eastern Africa. RSV and influenza activity were both elevated in a single country in Eastern 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 northern hemisphere temperate and subtropical areas, influenza-specific transmissibility was reported as below seasonal threshold (22); low (8) and moderate (1); transmissibility using syndromic data was reported as below seasonal threshold (23) and low (2). 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.