Core protocol for ECDC studies of vaccine effectiveness against symptomatic laboratory-confirmed influenza or SARS-CoV-2 infection at primary care level : version 1.0, September 2023

This document presents the core protocol for ECDC studies of CVE and IVE against symptomatic laboratoryconfirmed influenza or SARS-CoV-2 infection, respectively, at primary care level. This core protocol presents the main elements for a multicentre (multi-country) study of IVE/CVE at primary care level, outlining the agreed methods for collecting data related to influenza and SARS-CoV-2 at country level, and includes a plan for the pooled analysis. The combination of data from multiple study sites will allow for studies with more statistical power to meet more specific objectives. The protocol can be implemented for COVID-19 and/or influenza. The proposed method is a case-control study using a test negative design. The study population consists of people of all ages, belonging to the target group for COVID-19 or influenza vaccination, presenting to primary care with symptoms of acute respiratory infection (ARI) or influenza-like illness (ILI), and no contraindication for being vaccinated with the vaccine of interest. This protocol is adapted from the I-MOVE and I-MOVE+ generic protocols and the I-MOVE-COVID-19 generic protocol and is written in a generic manner. The specificities of each study site's influenza and/or COVID-19 VE study can be detailed in the individual site protocol annexes. This core protocol is primarily intended to guide the implementation of ECDC-funded studies. However, ECDC encourages the conduct of vaccine effectiveness studies, using this protocol as a basis, in countries not currently planning to participate in ECDC-funded studies. The use of consistent protocols will facilitate the comparability of study results across studies, countries, and study sites.