Rose, Angela McNicolay, NathalieSandonis-Martin, VirginiaMazagatos, ClaraPetrović, GorankaNiessen, F AnnabelMachado, AusendaLaunay, OdileDenayer, SarahSeyler, LucieBaruch, JoaquinBurgui, CristinaLoghin, Isabela IDomegan, LisaVaikutytė, RobertaHusa, PetrPanagiotakopoulos, GeorgeAouali, NasseraDürrwald, RalfHoward, JenniferPozo Sanchez, FranciscoSastre-Palou, BartoloméNonković, DianaKnol, Mirjam JKislaya, IrinaLuong Nguyen, Liem BinhBossuyt, NathalieDemuyser, ThomasDžiugytė, AušraMartínez-Baz, IvánPopescu, CorneliuDuffy, RóisínKuliešė, MonikaSoučková, LenkaMichelaki, StellaSimon, MarcReiche, JanineOtero-Barrós, María TeresaLovrić Makarić, ZvjezdanaBruijning-Verhagen, Patricia CjlGomez, VerónicaLesieur, ZinebBarbezange, CyrilVan Nedervelde, ElsBorg, Maria-LouiseCastilla, JesúsLazar, MihaelaO'Donnell, JoanJonikaitė, IndrėDemlová, ReginaAmerali, MarinaWirtz, GilTolksdorf, KristinValenciano, MartaBacci, SabrinaKissling, EstherMOVECOVID- 19 hospital study teamVEBIS hospital study team2023-12-132023-12-132023-11Euro Surveill. 2023 Nov;28(47):2300186.http://hdl.handle.net/20.500.12105/16792Introduction: Two large multicentre European hospital networks have estimated vaccine effectiveness (VE) against COVID-19 since 2021. Aim: We aimed to measure VE against PCR-confirmed SARS-CoV-2 in hospitalised severe acute respiratory illness (SARI) patients ≥ 20 years, combining data from these networks during Alpha (March-June)- and Delta (June-December)-dominant periods, 2021. Methods: Forty-six participating hospitals across 14 countries follow a similar generic protocol using the test-negative case-control design. We defined complete primary series vaccination (PSV) as two doses of a two-dose or one of a single-dose vaccine ≥ 14 days before onset. Results: We included 1,087 cases (538 controls) and 1,669 cases (1,442 controls) in the Alpha- and Delta-dominant periods, respectively. During the Alpha period, VE against hospitalisation with SARS-CoV2 for complete Comirnaty PSV was 85% (95% CI: 69-92) overall and 75% (95% CI: 42-90) in those aged ≥ 80 years. During the Delta period, among SARI patients ≥ 20 years with symptom onset ≥ 150 days from last PSV dose, VE for complete Comirnaty PSV was 54% (95% CI: 18-74). Among those receiving Comirnaty PSV and mRNA booster (any product) ≥ 150 days after last PSV dose, VE was 91% (95% CI: 57-98). In time-since-vaccination analysis, complete all-product PSV VE was > 90% in those with their last dose < 90 days before onset; ≥ 70% in those 90-179 days before onset. Conclusions: Our results from this EU multi-country hospital setting showed that VE for complete PSV alone was higher in the Alpha- than the Delta-dominant period, and addition of a first booster dose during the latter period increased VE to over 90%.engVoRhttp://creativecommons.org/licenses/by/4.0/AlphaDeltaEuropeSARS-CoV-2HospitalVaccine effectivenessCOVID-19HumansAdultBNT162 VaccineRNA, ViralSARS-CoV-2Vaccine EfficacyHospitalizationEuropeAtribución 4.0 Internacional379976662847230018610.2807/1560-7917.ES.2023.28.47.23001861560-7917Euro surveillance : bulletin Europeen sur les maladies transmissibles = European communicable disease bulletinopen access