Influenza Update N° 549

Overview

^{Published 22 October 2025 | For reporting Week 41, ending 12 October 2025}

Influenza

• Globally, influenza activity remained low, with influenza A viruses continuing to predominate.
• In the northern hemisphere temperate regions, influenza activity remained low and stable. Influenza percent positivity was elevated in Central America and the Caribbean, Northern Africa, and Northern Europe, with levels over 30% seen in Western and Middle Africa, Western, Southern and South-East Asia. An increase in activity was observed in countries in Central America and the Caribbean, Western and Middle Africa, Western, Southern and South-East Asia.
• In the southern hemisphere, influenza activity remained low and stable in most countries with elevated positivity (>10%) seen in single countries in Temperate South America, Eastern Africa and South-East Asia and percent positivity over 30% was seen in a single country in South-East Asia. No increasing trends in activity were seen in the Southern Hemisphere.
• In the transmission zones with elevated positivity, influenza A(H1N1)pdm09 predominated in Central America and the Caribbean, Northern and Middle Africa whereas influenza A(H3N2) was the predominant circulating subtype in Eastern Africa, Western, Southern and South-East Asia and Temperate South America. Influenza A(H1N1)pdm09 and influenza A(H3N2) were codominant in Western Africa and Northern Europe.

 

SARS-CoV-2

• Globally, SARS-CoV-2 positivity increased but remained at low levels, with some countries reporting elevated positivity (>10%) in Central America and the Caribbean, Tropical South America, South-West and Eastern Europe, and Eastern Asia. Small increases in activity were reported in single countries in Central America and the Caribbean and Tropical South America.

 

Respiratory Syncytial Virus (RSV)

• RSV percent positivity remained elevated in some countries in Central America and the Caribbean, Tropical and Temperate South America, with levels of over 30% in one country in Central America and the Caribbean. RSV positivity remained stable across most countries, with increases in activity seen in two countries in Central America and the Caribbean.

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 https://www.who.int/publications/i/item/WHO-2019-nCoV-integrated_sentinel_surveillance-2022.1.
 

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.