Domínguez, AngelaSoldevila, NúriaToledo, DianaGodoy, PereEspejo, ElenaFernandez, Maria AmeliaMayoral, José MaríaCastilla, JesúsEgurrola, MikelTamames, SoniaAstray, JenaroMorales-Suárez-Varela, MaríaThe Working Group Of The Project Pi/2023-01-252023-01-252017http://hdl.handle.net/10668/11546Influenza vaccination may limit the impact of influenza in the community. The aim of this study was to assess the effectiveness of influenza vaccination in preventing hospitalisation in individuals aged ≥ 65 years in Spain. A multicentre case-control study was conducted in 20 Spanish hospitals during 2013/14 and 2014/15. Patients aged ≥ 65 years who were hospitalised with laboratory-confirmed influenza were matched with controls according to sex, age and date of hospitalisation. Adjusted vaccine effectiveness (VE) was calculated by multivariate conditional logistic regression. A total of 728 cases and 1,826 matched controls were included in the study. Overall VE was 36% (95% confidence interval (CI): 22-47). VE was 51% (95% CI: 15-71) in patients without high-risk medical conditions and 30% (95% CI: 14-44) in patients with them. VE was 39% (95% CI: 20-53) in patients aged 65-79 years and 34% (95% CI: 11-51) in patients aged ≥ 80 years, and was greater against the influenza A(H1N1)pdm09 subtype than the A(H3N2) subtype. Influenza vaccination was effective in preventing hospitalisations of elderly individuals.enAttribution 4.0 Internationalhttp://creativecommons.org/licenses/by/4.0/effectivenesselderlyhospitalised cases, hospitalised controlsinfluenzamatched case–controlvaccinationAgedAged, 80 and overCase-Control StudiesFemaleHospitalizationHumansInfluenza A Virus, H1N1 SubtypeInfluenza A Virus, H3N2 SubtypeInfluenza VaccinesInfluenza, HumanLogistic ModelsMaleOutcome Assessment, Health CarePopulation SurveillanceSeasonsSpainVaccinationVaccine Potencyresearch article28857047open access10.2807/1560-7917.ES.2017.22.34.306021560-7917PMC5753443https://doi.org/10.2807/1560-7917.es.2017.22.34.30602https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5753443/pdf