^{Published 28 October 2025 | For reporting Week 42, ending 19 October 2025}

Influenza

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

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. Percent positivity was over 30% in one country in South-West Europe. Small increases in activity were reported in single countries in Eastern Africa and South-West Europe.

Respiratory Syncytial Virus (RSV)

• RSV percent positivity remained elevated in some countries in Western and Eastern Africa, and over 30% in two countries in Central America and the Caribbean. RSV positivity remained stable across most countries, with increases in activity in a few countries in Central America and the Caribbean. RSV and influenza activity were both elevated in a few countries of Central America and the Caribbean. 

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.