Global Respiratory Virus Activity: Weekly Update N° 601

Overview

In week 42 2026, globally, influenza positivity was below 10% and SARS-CoV-2 positivity increased slightly but remained low. Influenza positivity was below 10% in the northern hemisphere temperate and subtropical areas with a decrease in the reported specimens tested in the last four weeks. Influenza positivity decreased to around 5% in the southern hemisphere temperate and subtropical areas and remained around 15% in the tropical areas. RSV positivity also remained low globally.

Influenza

Globally, influenza detections remained low in week 42 with influenza A virus detections predominant.

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

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

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

SARS-CoV-2

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

Respiratory Syncytial Virus (RSV)

RSV positivity was elevated (>10%) in a few countries in Central America and the Caribbean and Temperate South America and in single countries in Western Africa and Southern Asia. Percent positivity was over 30% in a single country in Southern Asia. Increases in activity were observed in some countries in Tropical South America and in single countries in Central America and the Caribbean and Southern Asia. RSV and influenza activity were both elevated in countries in Central America and the Caribbean, Temperate South America, Western 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 below seasonal threshold in 14 countries, low in three countries and moderate in a single country; transmissibility using syndromic data was reported as below seasonal threshold in eight countries and low in two countries. Influenza-specific transmissibility was reported as below seasonal threshold in a single 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.