In its final 2021/22 influenza season, 13 sites from 8 different European countries, covering 21 hospitals and approximately 1125 GP for the TND studies and 1 nation-wide register-based cohort study in Finland participated in the DRIVE study. Low influenza circulation (in comparison to pre-pandemic flu seasons) was observed, and the flu season was influenced by several factors: 1) interference with the Omicron variant COVID-19 pandemic wave from November 2021 to February 2022 and 2) a late influenza epidemic peak surging in many European countries in March-April 2022. Despite the low influenza circulation, the DRIVE study was conducted as usual and brand-specific IVE estimations were obtained for 8 out of the 12 influenza vaccines marketed in Europe in the season 2021/22. This highlights the ability of the study network to cover the variety of influenza vaccine brands administered in Europe. DRIVE was not able to reach the sample size required to produce precise brand-specific estimates due to the low influenza circulation in Europe and the inability to expand the study site network in the current context. Thus, the majority of the IVE estimates were presenting very wide confidence intervals and consequently have to be interpreted with caution.
More information can be found in:
DRIVE IVE Results report 2021/22: Executive Summary
DRIVE IVE Results report 2021/22: Full Report