Effectiveness of XBB.1.5 monovalent COVID-19 vaccines during a period of XBB.1.5 dominance in EU/EEA countries, October to November 2023

Using a common protocol across seven countries in the European Union/European Economic Area, we estimated XBB.1.5 monovalent vaccine effectiveness (VE) against COVID-19 hospitalisation and death in ≥65-year-olds, during October-November 2023. We linked electronic records to construct retrospective cohorts and used Cox models to estimate adjusted Hazard Ratios and derive VE. VE for COVID-10 hospitalisation and death was, respectively, 67% (95%CI: 60-72) and 68% (95%CI: 44-82) in 65–79-year-olds, and 64% (95%CI: 49-75) and 74% (95%CI: 56-85) in ≥80-year-olds. Results indicate that periodic vaccination of individuals ≥65 years has an ongoing benefit, and support the current vaccination strategies in the EU/EEA.