Influenza Update N° 400

Overview

16 August 2021, based on data up to 01 August 2021

 

Information in this report is categorized by influenza transmission zones, which are geographical groups of countries, areas or territories with similar influenza transmission patterns. For more information on influenza transmission zones, see the link below:

Influenza Transmission Zones (pdf, 659kb)

• The current influenza surveillance data should be interpreted with caution as the ongoing COVID-19 pandemic has influenced to varying extents health seeking behaviours, staffing/routines in sentinel sites, as well as testing priorities and capacities in Member States. The various hygiene and physical distancing measures implemented by Member States to reduce SARS-CoV-2 virus transmission have likely played a role in reducing influenza virus transmission.
• Globally, despite continued or even increased testing for influenza in some countries, influenza activity remained at lower levels than expected for this time of the year. 
• In the temperate zones of the southern hemisphere, influenza activity remained at inter-seasonal levels.
• In the temperate zones of the northern hemisphere, influenza activity remained at inter-seasonal levels. 
• In the Caribbean and Central American countries, sporadic influenza B detections were reported from Mexico. 
• In tropical South America, one influenza A detection was reported from Peru. 
• In tropical Africa, influenza detections were reported in some countries in Western and Eastern Africa.
• In Southern Asia, influenza detections continued to be reported from Bangladesh, India and Nepal. 
• In South East Asia, one detection of Influenza A(H3N2) was reported from the Philippines.
• Worldwide, influenza B detections accounted for the majority of the low number of detections reported.
• National Influenza Centres (NICs) and other national influenza laboratories from 74 countries, areas or territories reported data to FluNet for the time period from 19 July 2021 to 01 August 2021* (data as of 2021-08-12 15:56:37 UTC). The WHO GISRS laboratories tested more than 186 515 specimens during that time period. 894 were positive for influenza viruses, of which 383 (42.8%) were typed as influenza A and 511 (57.2%) as influenza B. Of the sub-typed influenza A viruses, 51 (14.2%) were influenza A(H1N1)pdm09 and 307 (85.8%) were influenza A(H3N2). Of the characterized B viruses, 456 (99.6%) belonged to the B-Victoria lineage and 2 (0.4%) to the B-Yamagata lineage.
  

• During the COVID-19 pandemic, WHO encourages countries, especially those that have received the multiplex influenza and SARS-CoV-2 reagent kits from GISRS, to continue routine influenza surveillance, test samples from influenza surveillance sites for influenza and SARS-CoV-2 viruses where resources are available and report epidemiological and laboratory information in a timely manner to established regional and global platforms (see the guidance here: https://apps.who.int/iris/rest/bitstreams/1316069/retrieve).
• At the global level, SARS-CoV-2 percent positivity from sentinel surveillance remained around 20%. Activity increased in the WHO African, American and European Regions and showed a decline in the WHO Eastern Mediterranean Region. Activity was low from sentinel surveillance in the WHO South-East Asia and Western Pacific Regions this reporting period. 
• National Influenza Centres (NICs) and other national influenza laboratories from 34 countries, areas or territories reported data to FluNet for the time period from six WHO regions (African Region: 1;  Region of the Americas: 14;  Eastern Mediterranean Region: 2;  European Region: 10;  South-East Asia Region: 3;  Western Pacific Region: 4) reported to FluNet from sentinel surveillance sites for time period from 19 Jul 2021 to 01 Aug 2021* (data as of 2021-08-12 15:56:37 UTC). The WHO GISRS laboratories tested more than 118 519 sentinel specimens during that time period and 41 271 (34.8%) were positive for SARS-CoV-2. Additionally, more than 2 million non-sentinel or undefined reporting source samples were tested in the same period and 473 750 were positive for SARS-CoV-2. Further details are included at the end of this update.

 

 

 

 

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Source of data

The Global Influenza Programme monitors influenza activity worldwide and publishes an update every two weeks. The updates are based on available epidemiological and virological data sources, including FluNet (reported by the WHO Global Influenza Surveillance and Response System), FluID (epidemiological data reported by national focal points) and influenza reports from WHO Regional Offices and Member States. Completeness can vary among updates due to availability and quality of data available at the time when the update is developed.

^*It includes data only from countries reporting on positive and negative influenza specimens.