Estimated Population-Level Impact of Pneumococcal Conjugate Vaccines Against All-Cause Pneumonia Mortality Among Unvaccinated in 5 Latin American Countries

Background Pneumococcal conjugate vaccines (PCVs) provide strong direct protection in children, while limited data are available on their indirect effect on mortality among older age groups. This multicountry study aimed to assess the population-level impact of pediatric PCVs on all-cause pneumonia mortality among children >= 5 years of age, and invasive pneumococcal disease (IPD) cases in Chile.Methods Demographic and mortality data from Argentina, Brazil, Chile, Colombia, and Mexico were collected considering the >= 5-year-old population, from 2000 to 2019, with 1 795 789 deaths due to all-cause pneumonia. IPD cases in Chile were also evaluated. Time series models were employed to evaluate changes in all-cause pneumonia deaths during the postvaccination period, with other causes of death used as synthetic controls for unrelated temporal trends.Results No significant change in death rates due to all-cause pneumonia was detected following PCV introduction among most age groups and countries. The proportion of IPD cases caused by vaccine serotypes decreased from 29% (2012) to 6% (2022) among people aged >= 65 years in Chile.Discussion While an effect of PCV against pneumonia deaths (a broad clinical definition that may not be specific enough to measure indirect effects) was not detected, evidence of indirect PCV impact was observed among vaccine-type-specific IPD cases. This multicountry study evaluates the population-level impact of PCVs on pneumonia mortality in >= 5 year olds and IPD in Chile. PCV introduction showed no significant change in pneumonia death rates but reduced vaccine-type IPD cases in Chile, highlighting indirect effects.