Antunes, LilianaRojas-Castro, MadelynLozano, MarcosMartínez-Baz, IvánLeroux-Roels, IsabelBorg, Maria-LouiseOroszi, BeatrixFitzgerald, MargaretDürrwald, RalfJancoriene, LigitaMachado, AusendaPetrović, GorankaLazar, MihaelaSoučková, LenkaBacci, SabrinaHoward, JenniferVerdasca, NunoBasile, LucaCastilla, JesúsTernest, SilkeDžiugytė, AušraTúri, GergőDuffy, RoisinHackmann, CarolinKuliese, MonikaGomez, VerónicaMakarić, Zvjezdana LovrićMarin, AlexandruHusa, PetrNicolay, NathalieRose, Angela M. C.VEBIS SARI VE network team2026-01-132026-01-132025-03-09Influenza Other Respir Viruses. 2025 Mar;19(3):e70081. doi: 10.1111/irv.700811750-2640http://hdl.handle.net/10400.18/10687VEBIS SARI VE network team: Portugal: Ana Paula Rodrigues, Débora Pereira, Margarida Tavares, Susana Costa Maia e Silva, Paula Pinto, Cristina Bárbara, António Pais de Lacerda, Raquel Guiomar, Camila Henriques.We estimated the effectiveness of the adapted monovalent XBB.1.5 COVID-19 vaccines against PCR-confirmed SARS-CoV-2 hospitalisation during the BA.2.86/JN.1 lineage-predominant period using a multicentre test-negative case-control study in Europe. We included older adults (≥ 65 years) hospitalised with severe acute respiratory infection from November 2023 to May 2024. Vaccine effectiveness was 46% at 14-59 days and 34% at 60-119 days, with no effect thereafter. The XBB.1.5 COVID-19 vaccines conferred protection against BA.2.86 lineage hospitalisation in the first 4 months post-vaccination.engCase–Control StudyElderlySevere Acute Respiratory Infections (SARI)Test-Negative DesignVaccine EffectivenessCOVID-19SARS-CoV-2EuropeInfecções RespiratóriasDeterminantes da Saúde e da DoençaEstados de Saúde e de Doençajournal article10.1111/irv.700811750-265940059069