Influenza Update N° 520

Overview

 

^{Published 2 April 2025 | For reporting Week 12, ending 23 March 2025}

Influenza

• In the Northern hemisphere, activity continued to decline or remained the same in most countries. Minor increases in activity were reported in a few countries in Central America and Caribbean, Southwest and Eastern Europe, and Western, Southern and South-East Asia. Influenza positivity remained elevated (>10%) in the Americas (predominantly A(H1N1)pdm09 and A(H3N2)), Western (predominantly A(H1N1)pdm09) and Northern Africa (predominantly A(H3N2) and B viruses), Southwest and Northern Europe (A and B viruses in similar proportions), Eastern Europe (predominantly B viruses), Western and Southern Asia (predominantly A(H3N2) and B viruses), Central Asia (predominantly B viruses) and South-East Asia (predominantly A(H1N1)pdm09).
• In the Southern hemisphere, activity remained the same or decreased in all countries. Influenza positivity remained elevated in a few countries in Tropical South America, Eastern Africa (predominantly A viruses with A(H1N1)pdm09 and A(H3N2) in equal proportions), South-East Asia 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 and Western Africa where positivity remained elevated (>10%) and increased since the last report.

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://covid.comesa.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.