Influenza virus characterization - Summary Europe, August 2023

Compared with the 2021‑2022 influenza season, for sentinel surveillance the number of tested specimens has doubled, with a 4‑fold increase in influenza detections. For non‑sentinel surveillance, there has been a 16% de‑crease in the number of tested specimens, however detections have increased by 1.7‑fold. Overall the increase in testing and detections could be attributed to full relaxation of Covid19 restrictions with a “back to normal” respiratory disease surveillance attitude worldwide. Relative frequencies of type A vs B influenza viruses have changed, with influenza B detections increasing from 1.9% in 2021‑2022 to nearly 26% in the current season.