Pneumococcal carriage among young children attending daycare in Hungary, 12-13 years post-PCV13: a cross-sectional study.

Nasopharyngeal carriage of Streptococcus pneumoniae in children plays a key role in transmission and disease epidemiology, hence it is crucial to monitor colonisation. As PCV-15 has recently replaced PCV-13 in Hungary, the aim of the study was to survey colonisation epidemiology 12-13 years post-PCV-13. 401 children, attending day care centres at Northern Hungary (including Budapest) were screened between April 2022 and April 2023. The samples were collected with cotton swabs from both nostrils, the serotype and antibiotic susceptibility of the isolates was determined. Overall, the carriage rate was 16.5% (66/401 children), which is lower compared to previous data from Hungary. Serotypes 23B, 35F, 15A/F, 15B/C, 11A and 23A were most prevalent. Non-vaccine types (NVTs) accounted for 68.2%, the coverage of PCV-13, PCV-15 and PCV-20 would be 9.1%, 10.6% and 31.8%, respectively. The resistance of the isolates to erythromycin, clindamycin and tetracycline was 12.1%, 7.6% and 10.6%, respectively and penicillin non-susceptibility was 24.2%. Serotypes 23B and 15A/F and 35F contributed mostly to resistance. In summary, prevalence of NVTs is increasing and these are associated with higher resistance rates. Among vaccine types, those included in PCV-20 are most prevalent. Hence, vaccination with the highest coverage could be recommended.