Monovalent XBB.1.5 COVID-19 vaccine effectiveness against hospitalisations and deaths during the Omicron BA.2.86/JN.1 period among older adults in seven European countries: A VEBIS-EHR network study
Baltazar Nunes, James Humphreys, Nathalie Nicolay, Toon Braeye, Izaak Van Evercooren, Christian Holm Hansen, Ida Rask Moustsen‐Helms, Chiara Sacco, Massimo Fabiani, Jesús Castilla, Iván Martínez‐Baz, Hinta Meijerink, Ausenda Machado, Patrícia Soares, Rickard Ljung, Nicklas Pihlström, Anthony Nardone, Sabrina Bacci, Susana Monge, VEBIS-EHR working group
Abstract
BACKGROUND: We aimed to estimate XBB.1.5 vaccine effectiveness (VE) against COVID-19-related hospitalizations and deaths during BA.2.86/JN.1 predominance, among EU/EEA individuals with ≥65-years. RESEARCH DESIGN AND METHODS: We linked electronic health records to create historical cohorts in Belgium, Denmark, Italy, Navarre (Spain), Norway, Portugal and Sweden. We included individuals aged ≥65-years eligible for the autumnal 2023 COVID-19 vaccine. Follow-up started when ≥80% of country-specific sequenced viruses were BA.2.86/JN.1 (4/dec/23 to 08/jan/24) and ended 25 February 2024. At study site level, we estimated the vaccine confounder-adjusted hazard ratio (aHR) of COVID-19 hospitalizations and deaths between individuals with ≥14 days after vaccination versus unvaccinated in autumn 2023, overall, by time since vaccination and age groups. VE was estimated as (1-pooled aHR)x100 with a random-effects model. RESULTS: XBB.1.5 VE against COVID-19 hospitalizations was 50% (95%CI: 45 to 55) and 41% (95%CI: 35 to 46) in 65-79-year-olds and in ≥80-year-olds, respectively. VE against COVID19-related-death was 58% (95%CI: 42 to 69) and 48% (95%CI: 38 to 57), respectively, in both age groups. VE estimates against each outcome declined in all age groups over time. CONCLUSION: Monovalent XBB.1.5 vaccine had a moderate protective effect against severe and fatal COVID-19 likely caused by BA.2.86/JN.1 during the 2023/2024 winter, among persons aged ≥65.