Non-Linear Relationships Between Children Age And Pneumococcal Vaccine Coverage: Important Implications For Vaccine Prevention Strategies

Background: Streptococcus pneumoniae (S. pneumoniae) is an important pathogen causing both invasive and non-invasive infections in children, with significant morbidity and mortality worldwide. This study aimed to determine the potential relationships between age and vaccine coverage and between multiple phenotype-genotype characteristics of S. pneumoniae isolated from children.Methods: All S. pneumoniae isolates were tested for antimicrobial susceptibility, virulence genes, serotypes, and sequence types. The restricted cubic spline models were used to reveal potential relationships between children age and pneumococcal vaccine coverage.Results: For capsular-based vaccines, we observed a high coverage rate of 13-valent pneumococcal conjugate vaccine (PCV13, 85.8%) and a significantly non-linear relationship between children age and vaccine coverage (including PCV7, PCV10, and PCV13), with marked fluctuations in children aged < 2 years. For protein-based and pilus-based vaccine candidates, we demonstrated dynamic non-linear relationships between age and vaccine coverage, maintaining a stable and high coverage rate of ply and lytA for all age groups. Moreover, there were significantly high-dimensional corresponding relationships among multiple phenotype-genotype characteristics of S. pneumoniae isolates (such as ST271 associated with serotype 19F, PI-2, and extensively drug-resistance).Conclusions: Our findings suggest that the age for high PCV coverage being children aged >= 2 years and also provide important evidence for supporting ply and lytA as priority candidate targets for the development of new-generation protein vaccines. (C) 2021 Elsevier Ltd. All rights reserved.