Generic protocol for ECDC studies of influenza vaccine effectiveness against confirmed infection using healthcare worker cohorts - Version 2.0
This document presents the second version of the generic protocol for a prospective multi-country cohort study to measure the effectiveness of influenza vaccines in hospital-based HCWs during the 2023–24 winter season. This study is embedded in the CVE study set up under the VEBIS multi-country cohort study investigating CVE in HCWs.
Executive summary
Six study sites used the first version of this document during the 2022–23 winter season to determine the feasibility of performing this study in hospital-based HCWs. In three study sites, it was used to validate the use of saliva as an adequate sample for influenza testing in this population (report available by request). The IVE study was considered feasible and was permitted to start at the beginning of influenza circulation (week 40, 2023). Saliva could not be validated as an adequate sample for influenza testing due to the low number of influenza cases detected in symptomatic HCWs; therefore, this study will be repeated during the current 2023–24 season. The protocol for the pilot study is available in the document ‘Pilot protocol for influenza vaccine effectiveness against laboratory-confirmed influenza infections using healthcare worker cohorts’.
