Global Respiratory Virus Activity: Weekly Update N° 560

Overview

End-of year holiday season may affect the surveillance testing and reporting practices in one or more regions. Globally, influenza activity was elevated with positivity just under 25% in week 1 2026. SARS-CoV-2 activity remained stable and low overall. Influenza predominated and positivity was around 25% in the northern hemisphere temperate and sub-tropical areas, and just under 30% in the tropical areas. In the southern hemisphere temperate and subtropical areas, influenza positivity was low at around 5%.

Influenza

Globally, influenza detections appeared to decline; however, this could be an artifact due to delayed reporting in some regions. Influenza A viruses were predominant among influenza detections in all zones in week 1.

In the northern hemisphere, influenza percent positivity was elevated (>10%) in a few countries in North America and Western and Middle Africa.

Percent positivity was over 30% in countries in Central America and the Caribbean, Tropical South America, Northern Africa, Europe, and Western, Southern, South-East and Eastern Asia. Increases in activity were observed in countries in Central America and the Caribbean, Tropical South America, Northern Africa, Europe, and Western, Southern and South-East Asia.

In the southern hemisphere, influenza activity remained low overall although elevated positivity (>10%) was reported in a single countries in Tropical and Temperate South America; percent positivity was over 30% in single countries in Eastern Africa and Oceania. An increase in activity was observed in a single country in Temperate South America.

In the zones with elevated positivity, influenza A(H3N2) was predominant in all zones except Central America and the Caribbean and Tropical South America where there was codominance of influenza A(H1N1)pdm09 and A(H3N2) and Western and Middle Africa where influenza A(H1N1)pdm09 was predominant.

SARS-CoV-2

Globally, SARS-CoV-2 positivity remained stable and low, with some countries reporting elevated positivity (>10%) in South West and Eastern Europe and Temperate South America. A small increase in activity was reported in a single country in Eastern Europe.

Respiratory Syncytial Virus (RSV)

RSV activity was stable and low overall although elevated percent positivity (>10%) was reported in few countries in Western and Northern Africa, South West and Northern Europe, and Western Asia. Percent positivity was over 30% in a single country in Central America and the Caribbean and two countries in Southern Asia. An increase in activity compared to the previous reporting period was reported in single countries in Western Africa and Southern Asia and two countries in South West Europe. RSV and influenza activity were both elevated in single countries in Central America and the Caribbean, Northern Africa, South West Europe, Western and Southern Asia.

Severity assessment

The severity assessments here are reported from countries, areas and territories. Assessments for transmissibility can be reported based on syndromic parameters and/or influenza-specific parameters. In northern hemisphere temperate and subtropical areas, influenza-specific transmissibility was reported as below seasonal threshold (1) and moderate (1); in tropical areas, influenza-specific transmissibility was reported as below seasonal threshold in a single country. In northern hemisphere temperate and subtropical areas, transmissibility using syndromic data was reported as below seasonal threshold (11), low (6), moderate (11) and high (1).

 

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.

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.