Influenza Update N° 524

Overview

^{Published 30 April 2025 | For reporting Week 16, ending 20 April 2025}

Influenza

• In the Northern hemisphere, influenza positivity continued to decline or remained stable in most countries with small increases reported in single countries in Central America and the Caribbean, Tropical South America, Eastern Africa, Northern Europe and Western Asia. Influenza positivity remained elevated in North and Central America and the Caribbean (predominantly A(H1N1)pdm09), Tropical South America (predominantly A viruses), in Western Africa (predominantly A(H1N1)pdm09), Eastern Africa (predominantly A viruses), in Europe (predominantly A(H3N2) and B), in Western and South-East Asia (seasonal influenza viruses of all subtypes), Southern Asia (predominantly A(H3N2)) and Eastern Asia (predominantly A(H1N1)pdm09).
• In the Southern hemisphere, positivity remained stable with small increases in Temperate South America and South-East Asia. Influenza positivity was elevated in a few countries in Temperate South America and Oceania (predominantly A(H1N1)pdm09), Southern Africa (predominantly A(H3N2)), Eastern Africa and South-East Asia.

 

SARS-CoV-2

• Globally, positivity continued to remain low across reporting countries except for a few countries in Central America, Western Africa, South-West Europe and Western Asia where positivity was elevated.

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.