Influenza Update N° 410

10 January 2022
 | Emergency situation update
Influenza Update N° 410
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Overview

10 January 2022, based on data up to 26 December 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. 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 remains low but continued to increase especially in the temperate zones of the northern hemisphere. In several countries influenza activity reached the levels seen this time of year in pre-COVID-19 period.
  • 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. 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 although still low appeared to increase in some countries with detections of mainly influenza A(H3N2) viruses and in China B-Victoria lineage viruses.
  • In North America, influenza virus detections of predominately A(H3N2) among the subtyped increased and hospitalizations are increasing but remains low overall. RSV activity decreased in the USA and Canada.
  • In Europe, influenza activity continued to increase. Influenza A(H3N2) predominated.
  • In East Asia, influenza activity continued on an increasing trend in China, while influenza illness indicators and activity remained low in the rest of the subregion. Influenza B-Victoria lineage viruses predominated.
  • In the Caribbean and Central American countries, influenza A(H3N2) and B virus detections increased in some countries. 
  • In tropical South America, influenza A(H3N2) detections increased overall. Severe acute respiratory infection (SARI) levels were reported at extraordinary levels in Bolivia (Plurinational State). 
  • In tropical Africa, overall influenza activity continued on a decreasing trend, with both influenza A and B detected. 
  • In Southern Asia, influenza virus detections of predominately influenza A(H3N2) increased overall, although decreasing in a few countries. 
  • In South-East Asia, sporadic influenza detections were reported in the Philippines.
  • In the temperate zones of the southern hemisphere, influenza activity remained low overall, although increased detections of influenza A(H3N2) were reported in temperate South America.
  • National Influenza Centres (NICs) and other national influenza laboratories from 110 countries, areas or territories reported data to FluNet for the time period from 6 December 2021 to 26 December 2021* (data as of 2022-01-07 11:00:29 UTC). The WHO GISRS laboratories tested more than 522595 specimens during that time period. A total of 27153 were positive for influenza viruses, of which 19980 (73.6%) were typed as influenza A and 7173 (26.4%) as influenza B. Of the sub-typed influenza A viruses, 352 (4.4%) were influenza A(H1N1)pdm09 and 7625 (95.6%) were influenza A(H3N2). Of the characterized B viruses, 3 (~0%) belonged to the B-Yamagata lineage and 6819 (~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 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 increased to approximately 30%. Activity remained under 10% positivity in the Eastern Mediterranean, South-East Asian and Western Pacific Regions of WHO. In the other WHO Regions, an increasing trend in positivity was observed in recent weeks. Overall positivity from non-sentinel sites also increased and was at 25%.
  • NICs and other national influenza laboratories from 55 countries, areas or territories from six WHO regions (African Region: 1; Region of the Americas: 15; Eastern Mediterranean Region: 6; European Region: 25; South-East Asia Region: 4; Western Pacific Region: 4) reported to FluNet from sentinel surveillance sites for time period from 6 Dec 2021 to 26 Dec 2021 (data as of 2022-01-07 11:00:29 UTC). The WHO GISRS laboratories tested more than 81479 sentinel specimens during that period and 14285 (17.5%) were positive for SARS-CoV-2. Additionally, more than 2.2 million non-sentinel or undefined reporting source samples were tested in the same period and 258 139 were positive for SARS-CoV-2. Further details are included at the end of this update.

 

 

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)