Seasonal influenza is a major source of illness and mortality, especially among the elderly. Among the seasons 2014/2015–2016/2017, the determinants of vaccine uptake and their influence on health outcomes in older people living in Treviso were studied. A retrospective cohort analysis was carried out, integrating information from different health administrative databases, and several Poisson regression models were used to assess the efficacy of the influenza vaccination, while simultaneously controlling for confounding variables. MF59-adjuvanted trivalent inactivated vaccine was mostly used. Yearly data from about 83,000 older persons were studied. Vaccination coverage was approximately 50%; influenza vaccination uptake was independently associated with older age, male sex, increasing number of underlying chronic conditions, previous pneumococcal vaccination, annual expenses for specialist medical care, and general practitioner in charge of the elderly. Vaccination was linked to reduced mortality and influenza-related hospitalization rates after controlling for previously reported factors. Specifically, during the influenza season, the adjusted incidence rate ratio of mortality and influenza-related hospitalizations for vaccinated vs unvaccinated individuals was 0.63 and 0.86, respectively.
Death was predicted to have a comparable effectiveness across all age groups, but hospitalizations were shown to have a greater effect in patients over 75 years old. Vaccination was also successful in both men and women. The findings show that influenza immunization has a health advantage in the older population. Efforts should be concentrated on measures to boost vaccine uptake as an essential preventive measure.