Introduction: The objective was to estimate the effectiveness of inactivated trivalent vaccine (VE) in preventing hospital flu care (HFC) in Guadalajara, Castile-La Mancha (CLM), Spain, 2018-19 season., Material and Methods: Retrospective cohort study (40/2018 to 13/2019 weeks)., Sources: Microbiology programme; electronic medical history; population census (INE, 1/7/2018)., Cases: Population requiring HFC (hospital emergencies and/or emergency observation unit and/or hospital admissions), confirmed by antigenic test and/or PCR. Preventive fractions [PFv(vaccinated) and PFp(population)] and Necessary number of patients to be vaccinated (NNV) were calculated., Results: 228 HFT occurred [cumulative incidence rate (IR)=8.9/10 4 ; ≥65 years=65%; vaccination coverage=13% (≥65 years=58%); mortality=9%); maximum incidence in the 6th week (IR=1.7/10 4 ) (in CLM, in 4th)]. Highest peak of RSV occurred in the 3rd (in CLM, in the 52th). PFv (14-65 years) was 96% (PFp=58%) and in ≥65, 32% (PFp=21%). NNV=414. As in Spain, influenza virus A predominated, with A(H3N2) being 13% more prevalent (strain not included in the vaccine)., Conclusions: The season was delayed by sustained VRS circulation. The VE was lower than the national one. It is be essential to promote future campaigns to improve vaccination coverage., (Copyright © 2020 Elsevier España, S.L.U. All rights reserved.)