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

ImportanceIn 2014, the US Advisory Committee on Immunization Practices (ACIP) extended existing pneumococcal vaccination recommendations for adults aged ≥65 years to include 13-valent pneumococcal conjugate vaccine (PCV13), primarily to prevent non-bacteremic pneumonia.ObjectiveTo determine PCV13 effectiveness against all-cause inpatient plus outpatient medically-attended lower-respiratory tract infection (LRTI) and pneumonia among US older adults.DesignProspective, open cohort study following participants from 2016 to 2019. We conducted analyses in a self-matched framework, comparing outcomes during participants’ follow-up periods before and after receipt of PCV13.SettingKaiser Permanente Southern California (KPSC) integrated healthcare delivery system.ParticipantsAdults aged ≥65 years who received PCV13 between 2016-2019.ExposuresReceipt of PCV13 at ages ≥65 years, concordant with ACIP guidelines.Main outcomes and measuresWe estimated 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. We computed aHR estimates using Cox proportional hazards models. We defined vaccine effectiveness (VE) as (1–aHR)×100%. We also estimated PCV13-attributable absolute reductions in incidence of LRTI and pneumonia.ResultsObservations were available both before and after PCV13 receipt for 42,700 participants. Among these individuals, 1,419 experienced LRTI and 969 experienced pneumonia over approximately 26,000 combined years of follow-up before PCV13 receipt; 3,849 experienced LRTI and 2,727 experienced pneumonia over approximately 74,000 combined years of follow-up after PCV13 receipt. In adjusted analyses, 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. We estimated that 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 a five-year time horizon, one case of LRTI and pneumonia, respectively, was prevented for every 27 (14 to 116) and 42 (–97 to 268) individuals receiving PCV13.Conclusions and relevancePCV13 vaccination among older adults reduced the burden of medically-attended respiratory illness in this population.KEY POINTSQuestionDoes 13-valent pneumococcal vaccine (PCV13) reduce the burden of lower respiratory-tract infection (LRTI) and pneumonia among older adults?FindingsIn this longitudinal cohort study of adults aged 65 years and older from 2016-2019, PCV13 reduced incidence of LRTI and pneumonia episodes due to any cause by 9.5% and 8.8%, respectively. This effect corresponded to prevention of 0.7 and 0.5 episodes of LRTI and pneumonia, respectively, per 100 vaccinated persons each year. Protection from 23-valent pneumococcal polysaccharide vaccine was not apparent.MeaningAmong older adults, PCV13 vaccine administration substantially reduces the burden of medically-attended LRTI and pneumonia.