Weekly influenza overview

Week 47/2021 (22 – 28 November 2021)


  • Influenza activity was increasing throughout the European Region.
  • Of the 1471 specimens tested for influenza viruses for week 47/2021, from patients presenting with ILI or ARI symptoms to sentinel primary healthcare sites, 26 (2%) were positive for influenza virus; 24 for type A (the 14 subtyped were A(H3)) and 2 for type B (neither ascribed to a lineage). Influenza activity with influenza-confirmed patients in primary care or hospital settings with a rate of influenza virus detections above 10% has been reported by Kosovo (in accordance with Security Council resolution 1244 (1999)).
  • Hospitalized laboratory confirmed influenza cases were reported from ICU wards (1 influenza A virus), and from SARI cases (26 influenza A virus detections).
  • Influenza viruses were detected sporadically from non-sentinel sources (such as hospitals, schools, primary care facilities not involved in sentinel surveillance, or nursing homes and other institutions). Both influenza type A and type B viruses were detected.
Qualitative indicators

For week 47/2021, of 35 countries and areas reporting on intensity of influenza activity, 28 reported baseline-intensity and 7 reported low-intensity (Azerbaijan, Bosnia and Herzegovina, Estonia, Kyrgyzstan, Russian Federation, Slovakia and Kosovo (in accordance with Security Council resolution 1244 (1999))).

Of 35 countries and areas reporting on geographic spread of influenza viruses, 17 reported no activity, 13 reported sporadic spread, 1 reported local spread (Slovakia) and 4 reported regional spread (Kyrgyzstan, Russian Federation, Sweden, Kosovo (in accordance with Security Council resolution 1244 (1999))). 


Please note: 

  • Assessment of the intensity of activity indicator includes consideration of ILI or ARI rates. These ILI or ARI rates might be driven by respiratory infections other than influenza, including SARS-CoV-2, leading to observed increases in the absence of influenza virus detections
  • Assessment of intensity and geographic spread indicators includes consideration of sentinel and non-sentinel influenza virus detection data. Non-sentinel influenza virus detections, often higher, might translate into reporting of elevated geographic spread even in the absence of sentinel detections. 
© World Health Organization 2021
© European Centre for Disease Prevention and Control 2021
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The designation employed and the presentation of this material do not imply the expression of any opinion whatsoever on the part of the Secretariat of the World Health Organization concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers and boundaries.
* The administrative boundaries include spatial feature for Kosovo, this designation being without prejudice to position on status, and is in line with United Nations Security Council Resolution 1244 (1999) and the International Court of Justice Opinion on the Kosovo Declaration of Independence.
Administrative boundaries: © EuroGeographics, © UN-FAO.