Pneumococcal nasopharyngeal carriage, serotype distribution, and vaccination status in hospitalized children in Latvia: A cross-sectional study during the post-PCV13, pre-PCV15/PCV20 transition period
6 affiliations
- 1Department of Pediatrics, Riga Stradins University, Riga, Latvia
- 2Department of Pediatrics, Children’s Clinical University Hospital of Latvia, Riga, Latvia
- 3Department of Infectology, Riga Stradins University, Riga, Latvia
- 4Institute of Public Health, Riga Stradins University, Riga, Latvia
- 5Institute of Food Safety, Animal Health and Environment BIOR, Riga, Latvia
- 6Department of Human Physiology and Biochemistry, Riga Stradins University, Riga, Latvia
Abstract
Streptococcus pneumoniae remains a leading cause of invasive disease in children, and nasopharyngeal carriage surveillance is essential for monitoring vaccine-driven changes in serotype distribution. However, carriage data from the Baltic states are scarce. We conducted a cross-sectional study to assess pneumococcal carriage prevalence, serotype distribution, and associated factors in 321 hospitalized children aged 0–18 years at the Children’s Clinical University Hospital of Latvia between January 2021 and September 2022, a period representing the post-PCV13, pre-PCV15/PCV20 era. Pneumococcal carriage was detected by PCR targeting the lytA and sp2020 genes; serotyping was performed on PCR-positive samples. Overall carriage prevalence was 21.8% (70/321; 95% CI: 17.6–26.6%). Of the PCR-positive samples, 78.6% (55/70) were non-typeable and only 21.4% (15/70) yielded identifiable serotypes. Among these 15 typeable isolates, the most frequently detected serotypes were 20, 13, and 48, appearing in complex combinations, followed by 15A/15F, 23B1/23B, and 09N/09L—none of which are covered by PCV13; given the small number of typeable isolates, serotype findings are exploratory. PCV vaccination coverage was 63.2% (203/321), with PCV10 (Synflorix) predominating. No significant association was found between vaccination status and carriage prevalence (vaccinated: 25.6% vs. unvaccinated: 16.7%; p = 0.138). Children aged 1–5 years had the highest carriage prevalence at 30.9%. These data constitute the first comprehensive pneumococcal carriage assessment from the Baltic region during this transitional period and may serve as a reference for evaluating the impact of PCV15 and PCV20 following their introduction.
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BibTeX
@article{cupeca2026pneumococcal,
title = {{Pneumococcal nasopharyngeal carriage, serotype distribution, and vaccination status in hospitalized children in Latvia: A cross-sectional study during the post-PCV13, pre-PCV15/PCV20 transition period}},
author = {Hedija Cupeca and Indra Zeltina and Anita Villerusa and Larisa Savrasova and Ilze Grope and Maksims Mukans and Juris Kibilds and Angelika Krumina and Peteris Tretjakovs and Ludmila Viksna},
journal = {PLOS One},
year = {2026},
month = sep,
doi = {10.1371/journal.pone.0359297},
url = {https://doi.org/10.1371/journal.pone.0359297},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Pneumococcal nasopharyngeal carriage, serotype distribution, and vaccination status in hospitalized children in Latvia: A cross-sectional study during the post-PCV13, pre-PCV15/PCV20 transition period
AU - Hedija Cupeca
AU - Indra Zeltina
AU - Anita Villerusa
AU - Larisa Savrasova
AU - Ilze Grope
AU - Maksims Mukans
AU - Juris Kibilds
AU - Angelika Krumina
AU - Peteris Tretjakovs
AU - Ludmila Viksna
PY - 2026
DA - 2026/09/25
JO - PLOS One
DO - 10.1371/journal.pone.0359297
UR - https://doi.org/10.1371/journal.pone.0359297
AB - Streptococcus pneumoniae remains a leading cause of invasive disease in children, and nasopharyngeal carriage surveillance is essential for monitoring vaccine-driven changes in serotype distribution. However, carriage data from the Baltic states are scarce. We conducted a cross-sectional study to assess pneumococcal carriage prevalence, serotype distribution, and associated factors in 321 hospitalized children aged 0–18 years at the Children’s Clinical University Hospital of Latvia between January 2021 and September 2022, a period representing the post-PCV13, pre-PCV15/PCV20 era. Pneumococcal carriage was detected by PCR targeting the lytA and sp2020 genes; serotyping was performed on PCR-positive samples. Overall carriage prevalence was 21.8% (70/321; 95% CI: 17.6–26.6%). Of the PCR-positive samples, 78.6% (55/70) were non-typeable and only 21.4% (15/70) yielded identifiable serotypes. Among these 15 typeable isolates, the most frequently detected serotypes were 20, 13, and 48, appearing in complex combinations, followed by 15A/15F, 23B1/23B, and 09N/09L—none of which are covered by PCV13; given the small number of typeable isolates, serotype findings are exploratory. PCV vaccination coverage was 63.2% (203/321), with PCV10 (Synflorix) predominating. No significant association was found between vaccination status and carriage prevalence (vaccinated: 25.6% vs. unvaccinated: 16.7%; p = 0.138). Children aged 1–5 years had the highest carriage prevalence at 30.9%. These data constitute the first comprehensive pneumococcal carriage assessment from the Baltic region during this transitional period and may serve as a reference for evaluating the impact of PCV15 and PCV20 following their introduction.
SN - 1932-6203
ER -