Global Respiratory Virus Activity: Weekly Update N° 603

Overview

In week 44 2026, globally, influenza positivity was below 10% and SARS-CoV-2 positivity increased slightly but remained low. Influenza positivity continued to increase but remained just below 10% in the northern hemisphere temperate and subtropical areas. Influenza positivity decreased to below 5% in the southern hemisphere temperate and subtropical areas and remained above 10% in the tropical areas. RSV positivity also remained low globally.

Influenza

Globally, influenza detections remained low in week 44 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, Northern Europe and Southern and Eastern Asia and in a single countries in Eastern Europe and Western, Middle and Eastern Africa. Percent positivity was over 30% in some countries in Central America and the Caribbean, 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, South West Europe and Southern Asia and in single countries in Northern Europe, Middle Africa and Eastern Asia.

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

In the zones with elevated positivity, influenza A(H1N1)pdm09 was predominant in Northern Europe, Eastern Africa, Western and South-East Asia, and Oceania and influenza A(H1N1)pdm09 and A(H3N2) were codominant in Eastern Asia. Influenza A and B were codominant in Central America and the Caribbean, Temperate South America and Southern Asia and influenza B was predominant in Tropical South America, Western and Middle 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 and Western Asia. Percent positivity was over 30% in one country in Northern Africa. Small increases in activity were observed in some countries in South West Europe and Western Asia and in single countries in Northern Africa and Eastern Europe.

Respiratory Syncytial Virus (RSV)

RSV positivity was elevated (>10%) in a few countries in Central America and the Caribbean and in single countries in Tropical South America, Southern and Eastern Asia. Percent positivity was over 30% in single countries in Temperate South America and Southern Asia. Small increases in activity were observed in some countries in Central America and the Caribbean and in a single country in Temperate South America. RSV and influenza activity were both elevated in some countries in Central America and the Caribbean and in single countries in Southern and Eastern 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 10 countries and low in six countries; transmissibility using syndromic data was reported as below seasonal threshold in seven countries and low in one country. Influenza-specific transmissibility was reported as below seasonal threshold in a single country in the southern hemisphere temperate and subtropical areas and as low 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.