The first update of the ECDC ventilation guidance document contains: key new findings that emphasise four bundles of NPIs to reduce the risk of SARS-CoV-2 transmission in closed spaces; updated references on the evidence of transmission in closed spaces; recommendations based on the new evidence and on national and international guidance; and an overview of national guidance ventilation documents in the context of COVID-19 based on an inquiry sent to ECDC’s National Focal Points (NFPs) for Preparedness and Response and NFPs for Influenza and other respiratory diseases.