Influenza Update N° 398

Overview

19 July 2021, based on data up to 04 July 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 zone of the southern hemisphere, influenza activity remained at inter-seasonal levels.
• In the temperate zone of the northern hemisphere, influenza activity remained at inter-seasonal levels. 
• In the Caribbean and Central American countries, there were no influenza detections reported. 
• In tropical South America, only one influenza detection was reported. 
• In tropical Africa, a few influenza detections were reported in some countries in Western and Eastern Africa.
• In Southern Asia, a few influenza detections were reported from India, Nepal and Pakistan. 
• In South East Asia, a few influenza detections were 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 80 countries, areas or territories reported data to FluNet for the time period from 21 June 2021 to 04 July 2021* (data as of 2021-07-16 07:05:33 UTC).The WHO GISRS laboratories tested more than 156034 specimens during that time period. 631 were positive for influenza viruses, of which 143 (22.7%) were typed as influenza A and 488  (77.3%) as influenza B. Of the sub-typed influenza A viruses, 74 (59.2%) were influenza A(H1N1)pdm09 and 51 (40.8%) were influenza A(H3N2). Of the characterized B viruses, 2 (0.5%) belonged to the B-Yamagata lineage and 402 (99.5%) to the B-Victoria 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 global level, SARS-CoV-2 percent positivity from sentinel surveillance was slightly above 20%. Activity increased in the WHO African and European Regions and remained elevated in the WHO Region of the Americas and 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 43 countries, areas or territories reported data to FluNet for the time period from six WHO regions (AFRO: 1; AMRO: 15; EMRO: 3; EURO: 16; SEARO: 3; WPRO: 5) reported to FLUNET from sentinel surveillance sites for time period from 21 Jun 2021 to 04 Jul 2021* (data as of 2021-07-19 11:55:13 UTC). The WHO GISRS laboratories tested more than 69358 sentinel specimens during that time period and 15065 (21.7%) were positive for SARS-CoV-2. Additionally, more than 2 million non-sentinel or undefined reporting source type samples were tested in the same period 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.