Objectives: To evaluate the effectiveness of the influenza vaccination in reducing medical visits, hospital admissions, and deaths among the population > or =65 years of age in Friuli-Venezia Giulia.
Design: We conducted a retrospective and a prospective cohort study. For the retrospective study, we used data from the regional health electronic database. For the prospective study, we integrated this source of data with data provided by a sample of general practitioners.
Setting: The Friuli-Venezia Giulia region, Northeastern Italy.
Participants: The population > or =65 years of age assisted by the Regional Health Service.
Main outcome measures: Mortality from any cause, deaths, hospital admissions, and medical visits due to influenza, heart disease, and respiratory disease, also stratified by age and comorbidity.
Results: With the exception of some population subgroups, the retrospective study showed that the vaccination was not effective in reducing the risk of hospital admission and death. On the contrary, the vaccination was associated with an increase in hospital admissions due to influenza, heart disease, and respiratory disease (increased by 7%, 13%, and 17%, respectively). On the other hand, the prospective study showed an association between the vaccination and a 26% reduction in the risk of admissions for respiratory disease and a 21% reduction in the risk of all-cause death, whereas visits due to respiratory disease were increased by 55%.
Conclusions: Overall, the influenza vaccination appeared to have a low impact on the study cohorts. The vaccination was more effective in subjects <85 years of age and in those affected by comorbidity.