Effectiveness of influenza and pneumococcal vaccination in frail older adults

Abstract

OBJECTIVE: The aim of the study was to determine whether vaccinating older adults with PCV13 (pneumococcal conjugate vaccine) and/or PPSV23 (pneumococcal polysaccharide vaccine) and/or the influenza vaccine can reduce pneumonia-related hospitalizations and all-cause death. METHODS: Retrospective cohort of subjects ≥60 years who attended an outpatient clinic in Minas Gerais, Brazil (May 1, 2021 to April 26, 2024). Data regarding pneumonia hospitalizations, all-cause death, pneumococcal and influenza vaccination, demographic, and clinical characteristics were collected from an electronic health record (data in the cloud were available upon request). Only patients with valid data were included and were divided into groups based on their vaccination history, pneumococcal vaccinations (PVC13 and/or PPSV23), influenza vaccination, pneumococcal+influenza vaccinations, and unvaccinated, to calculate the association of vaccination with pneumonia hospitalizations and all-cause death by Cox proportional hazard models, adjusted for demographic and clinical factors. RESULTS: A total of 12,268 older adults were analyzed, with a median age of 79 (interquartile range 72–86), and 73% were female. Vaccination rates were 56% for influenza, 29% for pneumococcal vaccines, and 24% for both influenza and pneumococcal vaccines. Neither pneumococcal nor influenza vaccination alone showed a protective effect against pneumonia hospitalization. The combination of pneumococcal and influenza vaccines was associated with a 35% reduction in pneumonia hospitalization (HR 0.65; 95%CI 0.51–0.83). There was no association between vaccination and all-cause death, although the influenza vaccine tended to reduce this risk (HR 0.68; 95%CI 0.46–1.00; p-value 0.053). CONCLUSION: Despite low vaccination rates, the combination of influenza and pneumococcal vaccines reduces pneumonia hospitalizations among older adults by 35%.