Influenza Update N° 523

Overview

^{Published 23 April 2025 | For reporting Week 15, ending 13 April 2025}

Influenza

• In the Northern hemisphere, activity continued to decline or remained at low level in most countries. Minor increases in activity were reported in a few countries in Tropical South America, Western Africa, Eastern Europe and Eastern Asia. Influenza positivity remained elevated (>10%) in the Americas (predominantly A(H1N1)pdm09), Western Africa (predominantly A(H1N1)pdm09), Northern Africa, Eastern Africa (predominantly A(H1N1)pdm09 and A(H3N2)), in Europe (predominantly A(H3N2) and B viruses), and Western (predominantly A(H3N2) and B), Southern (predominantly A(H3N2)), Southeast (predominantly A(H1N1)pdm09 and B) and Eastern Asia (predominantly A(H1N1)pdm09).
• In the Southern hemisphere, influenza positivity was generally low (<10%) except in a few countries in Southern (predominantly A(H3N2)), Eastern Africa and Oceania (predominantly A(H1N1)pdm09). Activity remained at low level or decreased in all countries except for a small increase in a few countries in Temperate South America.

 

SARS-CoV-2

• Globally, activity decreased or remained at low level in most countries except for a few countries in Central America and the Caribbean, Southwest Europe and Western Asia where positivity was also elevated (>10%). Positivity was also elevated in single countries in Temperate South America and Eastern Asia.

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.