Impact of pneumococcal conjugate vaccine in children morbidity and mortality in Peru: Time series analyses

Streptococcus pneumoniae is the leading cause of bacterial pneumonia, meningitis and sepsis in children worldwide. Despite available evidence on pneumococcal conjugate vaccine (PCV) impact on pneumonia hospitalizations in children, studies demonstrating PCV impact in morbidity and mortality in middle-income countries are still scarce. Given the disease burden, PCV7 was introduced in Peru in 2009, and then switched to PCV10 in late 2011. National public healthcare system provides care for 60% of the population, and national hospitalization, outpatient and mortality data are available. We thus aimed to assess the effects of routine PCV vaccination on pneumonia hospitalization and mortality, and acute otitis media (AOM) and all cause pneumonia outpatient visits in children under one year of age in Peru. We conducted a segmented time-series analysis using outcome-specific regression models. Study period was from January 2006 to December 2012. Data sources included the National information systems for hospitalization, mortality, outpatient visits, and RENACE, the national database of aggregated weekly notifications of pneumonia and other acute respiratory diseases (both hospitalized and non-hospitalized). Study outcomes included community acquired pneumonia outpatient visits, hospitalizations and deaths (ICD10 codes J12-J18); and AOM outpatient visits (H65-H67). Monthly age- and sex-specific admission, outpatient visit, and mortality rates per 100,000 children aged <1year, as well as weekly rates for pneumonia and AOM recorded in RENACE were estimated. After PCV introduction, we observed significant vaccine impact in morbidity and mortality in children aged <1year. Vaccine effectiveness was 26.2% (95% CI 16.9-34.4) for AOM visits, 35% (95% CI 8.6-53.8) for mortality due to pneumonia, and 20.6% (95% CI 10.6-29.5) for weekly cases of pneumonia hospitalization and outpatient visits notified to RENACE. We used secondary data sources which are usually developed for other non-epidemiologic purposes. Despite some data limitations, our results clearly demonstrate the overall benefit of PCV vaccination in Peru.