Global Respiratory Virus Activity: Weekly Update N° 564

Overview

Globally, influenza activity continued to decrease since week 52 2025 and positivity was just above 10% in week 5 2026. SARS-CoV-2 activity remained low overall. Influenza predominated and positivity was around 10% in the northern hemisphere temperate and subtropical areas and around 15% in the tropical areas. In the southern hemisphere temperate and subtropical areas, influenza and SARS-CoV-2 positivity were both low.

Influenza

Globally, influenza detections continued to decline in week 5. Influenza A viruses were predominant among influenza detections, with a slight increase in the proportion of influenza B virus detections.

In the northern hemisphere, influenza percent positivity was elevated (>10%) in countries in North and Tropical South America, Western Africa, South and South-East Asia. Percent positivity was over 30% in countries in Central America and the Caribbean, Northern Africa, Europe, Western and Eastern Asia. Increases in activity were observed in countries in Central America and the Caribbean, Tropical South America, South West and Eastern Europe and Western and Southern Asia.

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

In the zones with elevated positivity, influenza A(H3N2) was predominant in most of the zones except Tropical South America where there was codominance of influenza A(H1N1)pdm09 and A(H3N2). Influenza B virus detections increased in countries in North America, Western Africa and Asia in week 5.

SARS-CoV-2

Globally, SARS-CoV-2 positivity remained stable and low, with single countries reporting elevated positivity (>10%) in Temperate South America and South West Europe. Small increases in activity were reported in a few countries in Temperate South America and Eastern Africa.

Respiratory Syncytial Virus (RSV)

Globally, RSV positivity remained stable and low, with a few countries reporting elevated positivity (>10%) in Central America and the Caribbean, Western Africa, Northern and South West Europe, Western and Central Asia. Small increases in activity were reported in countries in Western Africa, South West Europe, Western and Central Asia. RSV and influenza activity were both elevated in single countries in Central America and the Caribbean, Western Africa, Northern and South West Europe and Western 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 the northern hemisphere temperate and subtropical areas, influenza-specific transmissibility was reported as low (1); transmissibility using syndromic data was reported as below seasonal threshold (11), low (11), moderate (5) and high (3). Influenza-specific transmissibility was reported as below seasonal threshold in a single country in the southern hemisphere temperate and subtropical areas.

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.