Influenza Update N° 548

Overview

^{Published 15 October 2025 | For reporting Week 40, ending 05 October 2025}

Influenza

• Globally, influenza activity remained low, with influenza A viruses continuing to predominate. Different patterns were observed across hemispheres and transmission zones.
• In the northern hemisphere, over the past few weeks, influenza activity remained low and stable in most transmission zones in the temperate northern hemisphere. Influenza positivity was elevated in Central America and the Caribbean, Western, Northern, Eastern and Middle Africa, Western, Southern and South-East Asia and percent positivity was over 30% in countries in South-East Asia and Western Africa. An increase in activity was observed in countries in Central America and the Caribbean, Western and Eastern Africa, Western and South-East Asia.
• In the southern hemisphere, influenza activity remained low and stable in most reporting countries with elevated positivity (>10%) observed in single countries in Temperate South America, Eastern Africa, and percent positivity over 30% in single countries in South-East Asia and Oceania. An increase in activity was observed in a single country in South-East Asia.
• In the transmission zones with elevated positivity, influenza A(H1N1)pdm09 predominated in Central America and the Caribbean, Eastern and Middle Africa whilst influenza A(H3N2) was the predominant circulating subtype in Temperate South America, Western, Southern and South-East Asia and Oceania. Influenza A(H1N1)pdm09 and influenza A(H3N2) were codominant in Western Africa.

 

SARS-CoV-2

• Globally, SARS-CoV-2 positivity increased but remained at low levels, with some countries reporting elevated positivity (>10%) in North America, Central America and the Caribbean, Tropical South America, Europe, Western and Eastern Asia and percent positivity was over 30% in a few countries. Small increases in activity were reported in two countries in South-West Europe and one country in Tropical South America.

 

Respiratory Syncytial Virus (RSV)

• RSV positivity remained elevated in some countries in Central America and the Caribbean, Tropical and Temperate South America, Western Africa and Southern Asia and percent positivity was over 30% in a few countries. RSV positivity remained stable across the majority of reporting countries, with increases in activity reported in a few 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.