Influenza Update N° 521

Overview

 

^{Published 9 April 2025 | For reporting Week 13, ending 30 March 2025}

Influenza

• In the Northern hemisphere, influenza activity either continued to decline or remained stable in most countries. Slight increases were observed in a few countries in Eastern Africa, Southwest Europe, and Eastern Asia. Influenza positivity rates remained elevated (>10%) in North and Tropical South America (predominantly A viruses) and Central America and the Caribbean (predominantly A(H1N1)pdm09), in Africa (predominantly A viruses with variations in subtypes across sub-regions), in Europe (predominantly A(H3N2) and B), in Western, Central and Southern Asia (predominantly A(H3N2) and B), South-East Asia (predominantly A(H1N1)pdm09 and B) and Eastern Asia (predominantly A(H1N1)pdm09).
• In the Southern hemisphere, influenza activity remained the same or decreased in all countries. Influenza positivity remained elevated in a few countries in Tropical South America and Eastern Africa (predominantly A viruses), South-East Asia (predominantly A(H1N1)pdm09 and B viruses) and Oceania (predominantly A(H1N1)pdm09).

 

SARS-CoV-2

• Globally, activity continued to be low across reporting countries except for a few countries in Temperate South America, Western Africa and Eastern Asia where positivity remained elevated (>10%).

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.