We conducted a multicentre test-negative case–control study covering the period from October 2023 to January 2024 among adult patients aged ≥18 years hospitalised with severe acute respiratory infection in Europe. We provide early estimates of the effectiveness of the newly adapted XBB.1.5 COVID-19 vaccines against PCR-confirmed SARS-CoV-2 hospitalisation. Vaccine effectiveness was 49% overall, ranging between ...