Influenza Update N° 511

Overview

^{Published 29 January 2025 | For reporting Week 3, ending 19 January 2025}

Influenza

• In the Northern hemisphere influenza activity remained elevated in many regions, including Europe (due to seasonal influenza viruses of all subtypes), North America (predominantly influenza A), Central America and the Caribbean (predominantly influenza A(H3N2)), Western Africa (mostly influenza B), Northern Africa (mostly H3N2), and parts of Asia (predominantly influenza A(H1N1)pdm09). Activity increased in many parts of Europe, Asia and in one country in Western Africa based on reporting.
• In the Southern hemisphere, elevated activity was observed in a few countries in Tropical South America (predominantly influenza B viruses), Eastern Africa (predominantly influenza B viruses) and in Melanesia (mostly influenza A(H1N1)pdm09). In most reporting countries, activity was similar or decreased.

SARS-CoV-2

• Elevated activity persisted in some countries in South-West Europe, South America, Eastern and Southern Africa and South Asia. Increased SARS-CoV-2 activity was noted in single countries in Eastern Africa and South Asia. Activity remained low in most other countries showing stable or declining trends.

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.