Influenza Update N° 535

Overview

^{Published 16 July 2025 | For reporting Week 27, ending 6 July 2025}

Influenza

• Globally, influenza activity continued to decrease and was low with influenza A viruses predominant.
• In the Southern Hemisphere, over the past few weeks, trends in influenza activity varied by transmission zone, with an increasing trend in Oceania and a decreasing trend in Temperate and Tropical South America and Southern Africa. Compared to the previous week, influenza activity remained stable in most countries with a small increase reported from a single country in tropical South America. Influenza positivity remained elevated in countries of Tropical and Temperate South America, Southern and Eastern Africa and South-East Asia, and was over 30% in parts of Oceania.
• In the Northern Hemisphere, over the past few weeks, influenza activity mostly remained low and stable in most transmission zones except for Western Africa where an increasing trend was observed. Compared to the previous week, influenza remained stable in most countries with mostly small increases reported from single countries in Central America and the Caribbean, Tropical South America, Northern Europe, Eastern Africa and several countries in Southern Asia. Influenza positivity remained elevated in Central America and the Caribbean, Tropical South America, Western and Eastern Africa and South-East Asia, and was over 30% in parts of Southern Asia.
• Influenza A(H1N1)pdm09 predominated in the Americas, Western and Eastern Africa and Oceania whilst influenza A(H3N2) was the predominant circulating virus in Southern Africa, Western, Eastern and Southern Asia. Influenza A(H1N1)pdm09 and influenza A(H3N2) were co-dominant in South-East Asia.

 

SARS-CoV-2

• Globally, SARS-CoV-2 positivity remained stable and low across the majority of reporting countries. Positivity was elevated (>10%) in a few countries in Central America and the Caribbean, Northern and South West Europe, Northern and Western Africa, Western, Southern and South-East Asia. Small increases were reported in countries in Central America and the Caribbean, Northern Europe, Northern Africa and Southern Asia.

 

Respiratory Syncytial Virus (RSV)

• Among reporting countries, RSV positivity remained stable and low overall, with elevated activity and increases reported in a few countries in Central America and the Caribbean, Tropical and Temperate South America.

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.