Pediatric invasive pneumococcal disease spectrum before third-generation pneumococcal conjugate vaccine implementation.

Abstract

Background: After the implementation of pneumococcal conjugate vaccines (PCVs), besides the decrease of invasive pneumococcal disease (IPD), the clinical spectrum of the remaining cases changed, with many differences among serotypes. This study aimed to describe the clinical profile of IPD and the serotype distribution 15 years after PCV13 implementation and before the implementation of third-generation PCVs.

Methods: From 2017 to 2022, 128 French pediatric wards prospectively reported IPDs in children. Data were collected on demographics and clinical data, underlying conditions increasing the risk of IPD and outcome. Four clinical entities were considered: meningitis, bacteremia without source, bacteremic pneumonia, and other IPD.

Results: Among 931 IPD cases (median age of children 19.2 months, IQR:7.7-52.5), meningitis accounted for 36.4%, followed by bacteremia without source (31.6%), bacteremic pneumonia (20.5%) and other IPDs (11.5%). Underlying conditions were reported in 21.5% of children. Death was reported in 4.8% of IPD cases and meningitis represented 51.1% of fatal cases. PCV13 serotypes, mainly 3, 19A and 19F, still accounted for 15.0% of cases. PCV15 covered 6.2% more serotypes than did PCV13, whereas PCV20 covered 29.1% more serotypes than did PCV15. PCV20 non-PCV13 and PCV13 serotypes accounted for 33.3% and 11.1% of deaths, respectively. Serotype 24F ranked first and accounted for 16.4% of overall IPD cases.

Conclusion: From 2017 to 2022, among 931 IPD cases, PCV20 non-PCV13 serotypes (35.0% of cases) were implicated in 33.3% of deaths. Serotype 24F ranked first in overall IPD cases but is not included in third-generation PCVs.