Early Streptococcus pneumoniae serotype changes in Utah adults after the introduction of PCV13 in children

Abstract

Introduction: Pneumococcal conjugate vaccines (PCV) have indirect effects due to decreased Streptococcus pneumoniae colonization in vaccine recipients. We sought to determine whether the introduction of PCV13 in children led to changes in the epidemiology and clinical manifestations of invasive pneumococcal disease (IPD) in adults.

Methods: We described demographics, comorbidities, clinical manifestations, and serotypes of IPD in Utah adults before (November 2009-February 2010) and after (March 2010-March 2012) the introduction of PCV13 in children. We also compare serotypes causing IPD in Utah adults and children.

Results: After the introduction of PCV13 in the childhood vaccine program, the proportion of IPD due to PCV13 exclusive serotypes decreased significantly in Utah adults (64-40%, p=0.009), primarily due to a decline in serotype 7F (36-15%, p=0.008). There were non-significant increases in IPD due to Pneumococcal polysaccharide 23 (PPV23) unique serotypes and non-vaccine serotypes, most notably serotype 22F. Changes in the proportions of vaccine and non-vaccine serotypes were similar in adults and children. Meningitis was more commonly due to non-vaccine serotypes relative to non-meningitis cases (47% vs. 18%, p=0.007). When stratified by sex, decreases in PCV13 serotype IPD were only noted in men (76-33%, p=0.001).

Conclusions: Serotype epidemiology of IPD in adults closely follows that of children in the PCV13 era. Continued surveillance is needed to confirm whether replacement serotypes will lead to increases in pneumococcal meningitis and whether there are sex differences in the indirect effects of PCV vaccination in children.

Keywords: Epidemiology; Invasive pneumococcal disease; Pneumococcal vaccines; Streptococcus pneumoniae.