Factors associated to influenza vaccination among hospital's healthcare workers in the Autonomous Community of Madrid, Spain 2021-2022

Influenza vaccination (IV) aims primarily to protect high-risk groups against severe influenza-associated disease and death. It is recommended in Spain for high-risk groups, including Healthcare workers (HCWs). However, vaccination uptake has been consistently below desirable levels. The objective of this study were to evaluate influenza vaccination coverage using data from the regional vaccination registry, during 2021-2022 season, among HCWs in public hospitals in Autonomous Community of Madrid (CAM) and to explore factors associated with influenza vaccination. We conducted a cross-sectional study using administrative data retrieved from the Regional Department of Health data repositories. A multilevel logistic regression model was designed to estimate Level 1 (individual) and Level 2 (contextual) variables that are associated with HCWs vaccination. The study population was HCWs from 25 public hospitals in CAM who were active during the period of the influenza 2021-2022 vaccination campaign. The global influenza vaccination coverage (IVC) was 52.1 %. All study Level 1 variables were significantly associated with vaccine uptake. Greater IVC is associated with individual charac-teristics: female (OR1.14; 95 %CI 1.09-1.19), older age 59-69 years old (OR1.72; 95 %CI 1.60-1.84), born in Spain, medical staff, more than one high-risk condition (OR1.24; 95 %CI 1.10-1.40; respectively) and vaccinated in two previous campaigns (OR25.64; 95 %CI 24.27-27.09). IVC was highest among HCWs celiac disease (65.5 %) followed by diabetes mellitus (65.1 %) and chronic inflammatory disease (64.3 %). The hospital where the study subject worked also showed an effect on the vaccination uptake, although Level 2 variable (hospital complexity) was not positively associated. IVC in HCWs remains suboptimal. These findings may prove useful to tailor strategies to reach specific groups. It is recommended to delve into the identification of factors associated with the HCWs workplace that may have a positive impact on IV.