Core protocol for ECDC studies of vaccine effectiveness against hospitalisation with Severe Acute Respiratory Infection laboratory-confirmed with SARS-CoV-2 or with seasonal influenza Version 4.0

This version includes updates on methodology for CVE pooled analyses and inclusion on new variables for data collection, including on Respiratory Syncytial Virus (RSV) testing and vaccination status. The larger sample size achieved by combining data from multiple sites will provide more statistical power to meet more specific objectives. The protocol can be implemented for COVID-19 and/or influenza. A specific feasibility study to assess effectiveness of RSV immunisation products is being published separately.