Serotype diversity and risk factors for pneumococcal carriage among healthy children in Klang Valley, Malaysia: A pre-vaccination cross-sectional study.

Objectives: Carriage of Methods: A cross-sectional study conducted from August 2018 to May 2019 involved 101 healthy children aged 2-5 years from 30 childcare centers in Klang Valley, Malaysia. Oropharyngeal swabs, which are more acceptable for young children although less sensitive than nasopharyngeal swabs for pneumococcal detection, were collected and enriched in Todd Hewitt Broth before DNA extraction. Carriage was identified using real-time polymerase chain reaction (PCR) targeting Results: Pneumococcal carriage was detected in 39.6% (n = 40) of children, with 33 distinct serotypes identified. Both vaccine serotypes (VTs) and non-VTs were detected, with 67.5% of carriers colonized by multiple serotypes. Household size >5 members was significantly associated with carriage (adjusted odds ratio 4.62, 95% confidence interval 1.07-23.10, Conclusions: This study provides crucial pre-PCV baseline data on pneumococcal carriage, serotype diversity, and risk factors in children of Klang Valley, Malaysia. The high prevalence of NVTs and frequent co-colonization highlight the need for ongoing surveillance to detect serotype replacement and guide evaluation of higher-valency PCVs. These findings can inform national immunization policy and strengthen strategies for monitoring vaccine impact in Malaysia.