Influenza Update N° 412

7 February 2022
 | Emergency situation update
Influenza Update N° 412
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Overview

07 February 2022, based on data up to 23 January 2022

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. 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, influenza activity remained low and decreased this period after a peak at the end of 2021.
  • With the increasing detections of influenza during COVID-19 pandemic, countries are recommended to prepare for co-circulation of influenza and SARS-CoV-2. They are encouraged to enhance integrated surveillance to monitor influenza and SARS-CoV-2 at the same time, and step-up their influenza vaccination campaign to prevent severe disease and hospitalizations associated with influenza. Clinicians should consider influenza in differential diagnosis especially for high-risk groups for influenza, and test and treat according to national guidance.
  • In the temperate zones of the northern hemisphere, influenza activity decreased with detections of mainly influenza A(H3N2) viruses and B/Victoria lineage viruses reported.
  • In North America, influenza virus detections decreased and were predominantly A(H3N2) among those detected and subtyped. Influenza detections remained low compared to similar periods in past seasons (except 2020-2021). Respiratory syncytial virus (RSV) activity decreased in the USA and Canada.
  • In Europe, influenza activity appeared to decrease. Influenza A(H3N2) predominated.
  • In East Asia, influenza activity with mainly influenza B/Victoria lineage continued in an increasing trend in China, while influenza illness indicators and activity remained low in the rest of the subregion.
  • In Western Asia and Northern Africa, continuous influenza transmission has been reported in some countries.
  • In the Caribbean and Central American countries, some influenza activity was reported with influenza A(H3N2) predominating.
  • In tropical South America, some influenza activity was reported with influenza A(H3N2) predominating. 
  • In tropical Africa, influenza activity was reported in some countries with influenza A(H3N2) predominating followed by influenza B/Victoria lineage viruses.
  • In Southern Asia, influenza virus detections of predominantly influenza A(H3N2) remained elevated, although several countries reported a decrease in detections. 
  • In South-East Asia, sporadic influenza detections were reported by a few countries.
  • In the temperate zones of the southern hemisphere, influenza activity remained low overall, although increased detections of influenza A(H3N2) were reported in some countries in temperate South America.
  • National Influenza Centres (NICs) and other national influenza laboratories from 97 countries, areas or territories reported data to FluNet for the time period from 10 January 2022 to 23 January 2022* (data as of 2022-02-04 07:59:13 UTC).The WHO GISRS laboratories tested more than 608 024 specimens during that time period. 18 237 were positive for influenza viruses, of which 11 786 (64.6%) were typed as influenza A and 6451 (35.4%) as influenza B. Of the sub-typed influenza A viruses, 137 (3.2%) were influenza A(H1N1)pdm09 and 4116 (96.8%) were influenza A(H3N2). Of the characterized B viruses, 0 (0%) belonged to the B-Yamagata lineage and 6162 (100%) 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 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. Revised interim guidance has just been published here: https://covid.comesa.int/publications/i/item/WHO-2019-nCoV-integrated_sentinel_surveillance-2022.1.

  • At the global level, SARS-CoV-2 percent positivity from sentinel surveillance continued to increase overall during this reporting period. Positivity increased to above 30% in the Eastern Mediterranean and European Region of WHO, and above 60% in the Region of the Americas of WHO. Positivity also increased in the South-East Asian and Western Pacific Regions of WHO but remained under 20%. In the African Region of WHO, positivity decreased to under 20%. Overall positivity from non-sentinel sites also continued on an increasing trend.
  • National Influenza Centres (NICs) and other national influenza laboratories from 50 countries, areas or territories reported data to FluNet for the time period from six WHO regions (African Region: 1 Region of the Americas: 12; Eastern Mediterranean Region: 4; European Region: 26; South-East Asia Region: 3; Western Pacific Region: 4) reported to FluNet from sentinel surveillance sites for time period from 10 Jan 2022 to 23 Jan 2022* (data as of 2022-02-04 07:59:14 UTC). The WHO GISRS laboratories tested more than 167 575 sentinel specimens during that time period and 100 111 (59.7%) were positive for SARS-CoV-2. Additionally, more than 3 411 046 non-sentinel or undefined reporting source samples were tested in the same period and 2 149 621 were positive for SARS-CoV-2. Further details are included at the end of this update and in the surveillance outputs here.

 

 

Source of data

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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.

 

WHO Team
Global Influenza Programme (GIP)