2024•Epidemiology and Infectious DiseasesOpen access
Dynamics of Streptococcus pneumoniae serotype structure in children for the period 2016–2022
Irina N. Protasova, Irina V. Feldblium, Natalia V. Bakhareva, Ludmila V. Zinovieva, Sidorenko Sv
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Abstract
BACKGROUND: The need for microbiological monitoring of the distribution of pneumococcal serotypes is associated with changes that occur during routine immunization of children with pneumococcal vaccines. AIM: To characterize the changes in the serotype structure of Streptococcus pneumoniae obtained from healthy preschool children between 2016 and 2022. MATERIALS AND METHODS: In total, 1250 healthy children aged 6 years attending kindergartens were examined in multicenter studies (2016–2018 and 2020–2022). Nasopharyngeal pneumococcal isolates (n=265) were obtained using the culture method. S. pneumoniae serotype was determined using polymerase chain reaction. RESULTS: Between 2016 and 2018, the prevalence of pneumococcal carriage decreased from 27.3 to 17.3%, and by 2022, it increased to 25.6%. Moreover, the correspondence of S. pneumoniae serotypes to the antigenic composition of the 13-valent pneumococcal vaccine decreased from 48.8 to 9.4% and the composition of the 20-valent vaccine from 75.6 to 39.1%. The proportion of “non-vaccine” types of pneumococcus increased from 22% in 2016 to 61% in 2022. Among the “non-vaccine” serotypes/groups, 15AF, 6CD, 23A, and 35F/47F were predominant, and new variants were also discovered: 23B and 35B. The serotypes included in the 13-valent conjugate vaccine were detected among unvaccinated children and were represented by variants 19F, 6A and 6B, 23F. Throughout the observation period, pneumococci of serotypes/groups 15BC, 11AD, and 10A were detected with high frequency. CONCLUSIONS: Because of the elimination of a significant part of S. pneumoniae “vaccine” serotypes in 2016–2022, the concordance of circulating variants with the antigenic composition of pneumococcal conjugate vaccines significantly decreased. In addition, the new types detected with high frequency are not included in existing pneumococcal vaccines, which necessitates the creation of new immunobiological drugs for pneumococcal infection prevention.
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