The European Centre for Disease Prevention and Control (ECDC) periodically publishes influenza characterisation reports, giving an overview of circulating influenza viruses. These reports provide details on current vaccine strains, summarise the development of viruses since the last report and closely follow the main developments for the ongoing influenza season.
On 23 August 2021, the ECDC published the ninth virus characterisation period report for the 2020 to 2021 influenza season. As of week 28 of 2021, 943 influenza detections across the World Health Organization (WHO) European Region had been reported, of which 51% were type A viruses, with A(H3N2) and A(H1N1)pdm09 being approximately equally represented, and 49% were type B viruses, with 16 having been ascribed to a lineage, 13 being B/Victoria and three B/Yamagata. These figures represent a 99.4% drop in detections compared with the same period in 2020.
Source: ECDC, 23 August 2021