Influenza virus characterization: summary report, Europe, October 2022

Overview

The September 2022 characterization report, gave a breakdown of influenza detections across the World Health Organization (‎WHO)‎ European Region reported to TESSy up to week 39/2022 to complete the 2021-2022 season. This is the first report for the 2022-2023 influenza season. As of week 43/2022, 4 052 detections had been reported, resulting from extended late 2021-2022 season influenza activity. Of these detections, 87% were type A viruses, with A(‎H3N2)‎ dominating (‎71%)‎ over A(‎H1N1)‎pdm09 (‎29%)‎, and 13% type B of which 105 were ascribed to a lineage, with all being B/Victoria. This represents a 7-fold increase in detections compared to the 2021-2022 season, despite only a modest increase (‎3%)‎ in the number of samples tested. While there were 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, following an approximate two year period of low influenza virus circulation due to the COVID-19 pandemic, indications are that there will be an early start to the 2022-2023 season and a more intense epidemic than in 2021-2022.