OBJECTIVES: Promoprev is a program established by the Brazilian National Supplementary Agency (ANS) to promote health and prevention initiatives. Elderly individuals are highly susceptible to respiratory infections due to immunosenescence and comorbidities, therefore it is crucial to enhance healthcare assistance for this population. This retrospective and observational study aimed to assess the outcomes and costs of an elderly immunization program using a high-dose quadrivalent inactivated influenza vaccine (HD-QIV) within a Brazilian private healthcare plan during the influenza season.

METHODS: 246 patients aged ≥60 years were immunized with HD-QIV in the southern season of 2023 and the data from June 2023 to May 2024 were analyzed in comparison with the same cohort immunized with standard-dose vaccines (SD-TIV or SD-QIV) in the previous period, from June 2022 to May 2023. Outpatient visits and hospitalizations related to influenza and all-cause events were assessed by analyzing patient records grouped according to 189 ICD codes and the TUSS code (unified supplementary health terminology – medical procedure lists). The analysis enabled the estimation of healthcare resource utilization from the payer's perspective using the healthcare insurance database.

RESULTS: All-cause hospital costs for HD-QIV-vaccinated patients decreased by 25% vs SD-vaccinated and 83% vs non-vaccinated patients. The direct medical costs were 287,771 BRL for HD-QIV; 381,396 BRL for SD and 1,740,200 BRL for non-vaccinated patients. Overall, no influenza-related hospitalizations costs were reported for HD-QIV patients during the follow-up period.

CONCLUSIONS: The use of high-dose influenza vaccine in the elderly population was shown not only to prevent influenza-related events but also reduces hospitalizations due to other causes, leading to improved healthcare plan sustainability. Influenza HD vaccination campaigns could therefore enhance resource allocation resulting in substantial savings.