Pneumococcal serotypes and resistance profiles among children with and without PCV13 vaccination in Shenzhen, China

Streptococcus pneumoniae remains a major cause of lower respiratory tract infections (LRTIs) in children, and the introduction of pneumococcal conjugate vaccines has altered serotype circulation in many regions. In China, PCV13 has been available since 2016 as a voluntary, self-paying vaccine, resulting in uneven coverage across populations. This retrospective study analyzed 425 children under 14 years of age with culture-confirmed S. pneumoniae LRTIs treated at Shenzhen Children's Hospital between 2021 and 2022, comparing serotype distribution and antibiotic resistance profiles according to PCV13 vaccination status. A total of 40 serotypes were identified. Serotype 19F remained the most prevalent (n = 150), particularly among unvaccinated children, and was strongly associated with pneumonia. Serotypes 23A and 23F were also frequently detected. Vaccinated children exhibited lower proportions of PCV13-included serotypes, whereas unvaccinated children demonstrated higher rates of multidrug-resistant isolates. Additionally, emerging non-vaccine serotypes such as 15A and 6E were observed, suggesting early signs of serotype replacement under partial vaccine uptake. These findings highlight ongoing circulation of invasive and drug-resistant pneumococcal serotypes in children, especially those without PCV13 immunization. Strengthening vaccine coverage and sustaining serotype surveillance are critical to guide future immunization policy and antimicrobial stewardship strategies in China.