Do pneumococcal conjugate vaccines (PCVs) reduce childhood pneumonia mortality? An assessment across socioeconomic groups in Brazil

Abstract

BackgroundUnderstanding the real-world impact of pneumococcal conjugate vaccines (PCVs) on pneumonia mortality is critical, given the expectation that PCVs can substantially reduce the burden of pneumonia deaths in children under five years. However, surprisingly few post-vaccine introduction studies have estimated the benefit of PCVs for childhood mortality, and results have been inconsistent.\n\nMethodsWe investigated the long-term trends in child pneumonia mortality in Brazil (1980-present) and assessed the impact of PCV10 on childhood pneumonia mortality, both nationally and in municipalities stratified by socioeconomic status (SES), after the vaccine was introduced in Brazil in 2010.\n\nFindingsBetween 1980 and 2010, a period when Brazils Human Development Index (HDI) rose from 0.55 to 0.71, national pneumonia mortality in children under five decreased 10-fold. Despite rapid uptake of PCV10 following its introduction in 2010, our primary analytical method found no significant decline in national childhood pneumonia mortality, although a secondary analysis found a 10 percent decline in some but not all strata. However, at the municipal level we found significant reductions in childhood pneumonia mortality of up to 24% in low SES strata.\n\nInterpretationContrary to expectations, we found that PCV use led to at best modest savings in childhood pneumonia mortality at the national level in a middle-income country. In contrast, we found evidence that PCV led to larger reductions in low-income settings; a similar benefit might occur when PCVs are introduced in other low-SES settings. The long-term findings underscore that improvements in nutrition, hygiene, education, and healthcare play a major role in reducing pneumonia mortality.\n\nFundingThis work was funded by a grant from the Bill & Melinda Gates Foundation (OPP1114733). DMW also acknowledges support from the Bill and Melinda Gates Foundation (OPP1176267) and the National Institute of Allergy and Infectious Diseases (R01AI123208)