Prevalence of pneumonia in early childhood and associated factors in a location with high pneumococcal vaccination coverage

Pneumonia constitutes a leading cause of death in children from low- and middle-income countries. We aimed to describe the prevalence and the factors associated with pneumonia in children aged from 0 to 6 years in a location with high pneumococcal vaccination coverage. The occurrence of at least one episode of pneumonia diagnosed by a physician as reported by the mother was investigated at the 12-, 24-, and 48-month, and 6-year follow-ups of the 2015 Pelotas (Brazil) birth cohort. The independent variables included family and child characteristics at birth, breastfeeding, and vaccinal status. Prevalence ratios (PR) with 95% confidence interval (95%CI) were estimated by unadjusted and multivariable Poisson regressions with robust variance. At the 12-, 24-, 48-month, and 6-year follow-ups 4,014, 4,006, 3,997, and 3,862 children were assessed, respectively. Prevalence from 0 to 6 years equaled 16.7% (95%CI: 15.5-18.0). Within the first, second, 2-4 and 4-6 years of age the prevalence of at least one episode of pneumonia totaled 7.9%, 5.9%, 6.7%, and 3.4%, respectively. Higher maternal parity (adjusted PR = 1.75, 1.61, and 2.0 at the first, second, and 4-6 years, respectively) and prematurity (adjusted PR = 1.39 and 1.49 at the first and second years of life, respectively) constituted the factors most consistently associated with an increased risk of pneumonia. Almost one in every five children aged 6 years had a positive history of pneumonia, mainly in their first year of life. Greater maternal parity was the strongest and most consistent factor associated with a higher prevalence of pneumonia in childhood.