Rose, Angela McNicolay, NathalieSandonis-Martin, VirginiaMazagatos, ClaraPetrović, GorankaBaruch, JoaquinDenayer, SarahSeyler, LucieDomegan, LisaLaunay, OdileMachado, AusendaBurgui, CristinaVaikutytė, RobertaNiessen, F AnnabelLoghin, Isabela IHusa, PetrAouali, NasseraPanagiotakopoulos, GeorgeTolksdorf, KristinHorváth, Judit KrisztinaHoward, JenniferPozo Sanchez, FranciscoGallardo, VirtudesNonković, DianaDžiugytė, AušraBossuyt, NathalieDemuyser, ThomasDuffy, RóisínLuong Nguyen, Liem BinhKislaya, IrinaMartínez-Baz, IvánGefenaite, GiedreKnol, Mirjam JPopescu, CorneliuSoučková, LenkaSimon, MarcMichelaki, StellaReiche, JanineFerenczi, AnnamáriaDelgado-Sanz, ConcepcionLovrić Makarić, ZvjezdanaCauchi, John PaulBarbezange, CyrilVan Nedervelde, ElsO'Donnell, JoanDurier, ChristineGuiomar, RaquelCastilla, JesúsJonikaite, IndrėBruijning-Verhagen, Patricia CjlLazar, MihaelaDemlová, ReginaWirtz, GilAmerali, MarinaDürrwald, RalfKunstár, Mihály PálKissling, EstherBacci, SabrinaValenciano, MartaI-MOVE-COVID-19 hospital study teamVEBIS hospital study team2023-12-132023-12-132023-11Euro Surveill. 2023 Nov;28(47):2300187.http://hdl.handle.net/20.500.12105/16791Introduction: The I-MOVE-COVID-19 and VEBIS hospital networks have been measuring COVID-19 vaccine effectiveness (VE) in participating European countries since early 2021. Aim: We aimed to measure VE against PCR-confirmed SARS-CoV-2 in patients ≥ 20 years hospitalised with severe acute respiratory infection (SARI) from December 2021 to July 2022 (Omicron-dominant period). Methods: In both networks, 46 hospitals (13 countries) follow a similar test-negative case-control protocol. We defined complete primary series vaccination (PSV) and first booster dose vaccination as last dose of either vaccine received ≥ 14 days before symptom onset (stratifying first booster into received < 150 and ≥ 150 days after last PSV dose). We measured VE overall, by vaccine category/product, age group and time since first mRNA booster dose, adjusting by site as a fixed effect, and by swab date, age, sex, and presence/absence of at least one commonly collected chronic condition. Results: We included 2,779 cases and 2,362 controls. The VE of all vaccine products combined against hospitalisation for laboratory-confirmed SARS-CoV-2 was 43% (95% CI: 29-54) for complete PSV (with last dose received ≥ 150 days before onset), while it was 59% (95% CI: 51-66) after addition of one booster dose. The VE was 85% (95% CI: 78-89), 70% (95% CI: 61-77) and 36% (95% CI: 17-51) for those with onset 14-59 days, 60-119 days and 120-179 days after booster vaccination, respectively. Conclusions: Our results suggest that, during the Omicron period, observed VE against SARI hospitalisation improved with first mRNA booster dose, particularly for those having symptom onset < 120 days after first booster dose.engVoRhttp://creativecommons.org/licenses/by/4.0/COVID-19EuropeSARS-CoV-2HospitalOmicronVaccine effectivenessCOVID-19PneumoniaHumansAdultCOVID-19 VaccinesVaccine EfficacySARS-CoV-2HospitalizationEuropeRNA, MessengerAtribución 4.0 Internacional379976652847230018710.2807/1560-7917.ES.2023.28.47.23001871560-7917Euro surveillance : bulletin Europeen sur les maladies transmissibles = European communicable disease bulletinopen access