Vaccine Acceptance and Delivery Strategies in Healthcare Workers at an Italian Hospital, 2015–2024

Abstract Healthcare workers (HCWs) play a pivotal role in the control and prevention of infectious diseases. However, their vaccination rates often fall short, posing risks to patient care, healthcare system performance, and their own safety due to regular exposure to pathogens. This study explores ten years of influenza vaccination trends and recent COVID-19 co-administration practices in a large Italian hospital, aiming to assess acceptance drivers and optimize immunization strategies. A retrospective cohort study reviewed vaccination records from 6,422 HCWs from 2015 to 2024, assessing uptake rates across various vaccination delivery models. Mixed-effects logistic regression was used to evaluate how sociodemographic, professional, and organizational factors influenced vaccine acceptance. Influenza vaccination peaked at 46% during the first COVID-19 year, then returned to pre-pandemic levels. Co-administration rose significantly, with a 118.94% increase from 2021 to 2022. Acceptance of influenza vaccination was highest among physicians (OR 31.34, 95% CI 25.05-39.50) and nurses (OR 8.67, 95% CI 7.56-11.97), while administrative staff showed the lowest uptake. Conversely, co-administration acceptance declined with age (OR 0.45, 95% CI 0.39-0.69), with no significant differences across professional categories. Delivery models strongly influenced uptake: “open-day” events substantially improved influenza vaccination rates (OR 20.19, 95% CI 18.11-24.17), while the hospital outpatient clinic proved most effective for co-administration (OR 31.01, 95% CI 29.97-45.25). This study reveals key patterns in vaccination behaviours and organizational effectiveness. The decline in influenza coverage after the pandemic peak may reflect vaccine fatigue and reduced perceived risk. Implementing diverse, flexible strategies and continuous education is essential to sustain vaccination coverage among HCWs. Key messages • Targeted public health strategies are needed to address age-related hesitancy and boost vaccine uptake among all HCW groups. • Flexible, context-specific delivery models are key public health tools to improve and sustain HCW vaccination coverage.