Lower respiratory infections mortality among Brazilians under-five before and after national pneumococcal conjugate vaccine implementation.

Background: Studies on the impact of pneumococcal conjugate vaccines (PCV) on mortality, especially among preschoolers are scarce. We aimed to assess time trend mortality from lower respiratory infections (LRI), taken as a proxy of pneumonia, from 1990 to 2017.

Methods: This ecological study assessed the mortality rate among Brazilians under-five before and after the national PCV-10 implementation in 2010. Pneumococcal meningitis (PM) and diarrheal diseases (DD) were included as a "positive and negative controls", respectively. Trend analysis was performed through Global Burden of Disease estimates. Joinpoint regression modeling was used to describe trends in mortality and to identify time points of its statistically significant decreases throughout the study period.

Results: There was a sustainable reduction in mortality rates for these three diseases, with no relevant changes in the secular trends for LRI and PM after the PCV-10 implementation. For LRI, PM, and DD the higher and statistically significant (p < 0.05) annual percent change reduction occurred between 2000 and 2003, (-8.3%), 1997-2000 (-11.9%), and 1990-1994. (-13.8%), respectively, i.e., several years before the nationwide implementation of PCV-10. Moreover, for LRI the annual percent change (from -5.9 to -8.8) verified from 1990 to 2009, i.e., 20 years before countrywide vaccination, was comparable to that observed during the PCV era, that is, from minus 5.8 to minus 7.8, between 2010 and 2017.

Conclusion: Mortality from LRI, PM, and DD decreased over time, irrespective of national PCV-10 implementation in Brazil. Other factors such as healthcare delivery, socioeconomic status improvement, and health interventions may have impacted this secular trend.