Distribution of invasive Streptococcus pneumoniae serotypes before and 5 years after the introduction of 10-valent pneumococcal conjugate vaccine in Brazil

Abstract

Background: In March 2010, the 10-valent pneumococcal conjugate vaccine (PCV10) was introduced into the routine immunization program in Brazil. We describe the pneumococcal serotypes that caused invasive pneumococcal diseases (IPD) before and after the introduction of PCV10 using data from a national laboratory-based surveillance system.

Method: We compared the prevalence of vaccine types (VT) and non-vaccine types (NVT) of Streptococcus pneumoniae in three periods, pre-PCV10 (January/2005-December/2009), early post-PCV10 (January/2010-December/2013), and late post-PCV10 (January/2014-December/2015), by episode in meningitis and non-meningitis cases and by age group. Changes in serotype prevalence in the early and late post-PCV10 periods were determined using pre-PCV10 period as a reference.

Results: A total of 8971 IPD isolates from patients aged 2 months to 99 years were analyzed. In the late post-PCV10 period, the VT-IPD reduction in the 2-month to 4-year age group was 83.4% for meningitis and 87.4% for non-meningitis cases; in the age groups 5-17 years, 18-64 years, and ≥65 years, VT declined by 56.1%, 54.1%, and 47.4%, respectively, in meningitis cases, and by 60.9%, 47.7%, and 53.4%, respectively, in non-meningitis cases. NVT-IPD increased throughout the study period, driven mainly by serotypes 3, 6C, and 19A, which remained the predominant types causing IPD in the late post-PCV10 period.

Conclusion: We observed direct and indirect PCV10 protection against IPD caused by VT and a shift in the distribution of serotypes 5 years after the introduction of PCV10. Continued IPD surveillance is needed to evaluate the sustainability of the high prevalence of serotypes 3, 6C, and 19A, which were not included in PCV10.

Keywords: 10-valent pneumococcal conjugate vaccine; Pneumococcal conjugate vaccine; Pneumococcal serotypes; Streptococcus pneumoniae.