Influenza virus characterization: summary report, Europe, June 2022
Overview
This is the seventh report for the 2021-2022 influenza season.
The May 2022 characterization report gave a breakdown of influenza detections across the World Health Organization (WHO) European Region reported to TESSy up to week 20/2022. As of week 25/2022, 138 352 detections had been reported (a rise of over 5 000 since week 20/2022) resulting from extended late season influenza activity. Of these 138 352 detections, 98% were type A viruses, with A(H3N2) (92%) dominating over A(H1N1)pdm09 (8%), and 2% type B of which only 125 were ascribed to a lineage, with all but two being B/Victoria.
This represents a large increase (137 418, 148-fold) in detections compared to the 2020-2021 season, on the back of a great increase (1 900 146, 200%) in the number of samples tested. However, while there have been clear indications of an influenza epidemic in 2021-2022 with the epidemic threshold of 10% positivity within sentinel specimens having been crossed for 17 weeks as of week 25/2022 (unlike in 2020-2021), numbers of detections are reduced compared to earlier seasons (e.g., 16% reduced compared to 2019-2020). The increased testing but reduced number of influenza detections is undoubtedly related to the emergence of SARS-CoV-2 and measures introduced to combat it.
