Effectiveness of 13-valent pneumococcal conjugate vaccine against medically-attended lower respiratory tract infection and pneumonia among older adults

Abstract

Abstract Background Among older adults, 13-valent pneumococcal conjugate vaccine (PCV13) has been found efficacious against non-bacteremic pneumonia associated with vaccine-serotype pneumococci. However, the burden of lower-respiratory tract infection (LRTI) and pneumonia preventable by direct immunization of older adults continues to be debated. Methods We analyzed data from an open cohort of adults aged ≥65 years enrolled in Kaiser Permanente Southern California health plans from 2016 to 2019, who received PCV13 concordant with US Advisory Committee on Immunization Practices guidelines. We estimated PCV13 vaccine effectiveness (VE) via the adjusted hazards ratio (aHR) for first LRTI and pneumonia episodes during each respiratory season, comparing PCV13-exposed and PCV13-unexposed time at risk for each participant using a self-matched inference framework. Analyses used Cox proportional hazards models, stratified by individual. Results Among 42,700 adults who met inclusion criteria, VE was 9.5% (95% confidence interval: 2.2% to 16.3%) against all-cause medically-attended LRTI and 8.8% (–0.2% to 17.0%) against all-cause medically-attended pneumonia. In contrast, we did not identify evidence of protection against LRTI and pneumonia following receipt of 23-valent pneumococcal polysaccharide vaccine. PCV13 prevented 0.7 (0.2 to 1.4) and 0.5 (0.0 to 1.0) cases of LRTI and pneumonia, respectively, per 100 vaccinated persons annually; over 5 years, one case of LRTI and one case of pneumonia were prevented for every 27 and 42 individuals vaccinated, respectively. Conclusions PCV13 vaccination among older adults substantially reduced incidence of medically-attended respiratory illness. Direct immunization of older adults is an effective strategy to combat residual disease burden associated with PCV13-type pneumococci.