Global Respiratory Virus Activity: Weekly Update N° 557

Overview

Globally, influenza activity was elevated with positivity just under 20% in week 49. SARS-CoV-2 activity remained stable and low overall. Influenza predominated and positivity was at or above 10% in the northern hemisphere temperate and sub-tropical, southern hemisphere temperate and subtropical, and the tropical areas.

Influenza

Globally, influenza detections continued to increase with influenza A viruses predominant among influenza detections in all zones.

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

In the southern hemisphere, influenza activity remained low overall although elevated positivity (>10%) was reported in a few countries in Tropical and Temperate South America, Middle and Eastern Africa, and Oceania; percent positivity was over 30% in a single country in Eastern Africa. No increases in activity compared to the previous week were observed.

In the zones with elevated positivity, influenza A(H3N2) was predominant in all zones except Central America and the Caribbean where there was codominance of influenza A(H1N1)pdm09 and A(H3N2) and Tropical South America and Northern 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 Temperate South America, Europe and Southern Asia. Percent positivity was over 30% in a single country in South West Europe. Small increases in activity were reported in countries in Northern and South West Europe and Southern Asia.

Respiratory Syncytial Virus (RSV)

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

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.