Prevalence and serotype distribution of nasopharyngeal carriage of Streptococcus pneumoniae in Vietnam: a systematic review and meta-analysis

Background Streptococcus pneumoniae ( S. pneumoniae ) is a leading cause of childhood morbidity and mortality worldwide. While pneumococcal conjugate vaccines (PCVs) have significantly reduced the global burden of pneumococcal disease, Vietnam has yet to introduce PCV into their National Immunisation Program. Better understanding of pneumococcal disease in Vietnamese children is key to informing vaccination policy, including PCV product selection. The aim of this study was to assess the prevalence, serotype distribution, and antimicrobial susceptibility patterns of nasopharyngeal carriage of S. pneumoniae among children in Vietnam. Methods We conducted a systematic review and meta-analysis of S. pneumoniae carriage studies in Vietnamese children under 18 years of age. Seven international biomedical research databases and 13 key Vietnamese-language journals were searched without language or publication date restrictions. The Joanna Briggs Institute critical appraisal tools were used to assess the quality of articles. We extracted data on the prevalence of S. pneumoniae carriage and the serotype distribution. Where available, we also extracted the proportions of isolates that were non-susceptible to selected antibiotics. The pooled prevalence, serotype distribution, and antibiotic resistance rates were calculated with 95% confidence intervals (CIs) using random-effects models. Findings A total of 1197 studies were searched, of which 594 unique studies were identified and screened. 15 studies, conducted between 1996 and 2020, were included in the systematic review and meta-analysis. The pooled prevalence of nasopharyngeal carriage of S. pneumoniae among Vietnamese children was 33% (95% CI: 28%–39%). The most common vaccine serotypes associated with colonisation were 6A (23%), 19F (17%), 6B (15%), 23F (10%), 14 (8%), and 19A (3%). High non-susceptibility rates were observed for penicillin (64%), macrolides (70%–91%), sulfamethoxazole–trimethoprim (70%), tetracycline (84%), and several other antibiotics. Moderate to low non-susceptibility rates were observed for amoxicillin (22%), amoxicillin-clavulanate (6%), moxifloxacin (1%), vancomycin (1%), and rifampicin (0%). Interpretation The prevalence of S. pneumoniae nasopharyngeal carriage in children, a surrogate for potential invasive disease, was high in Vietnam, with substantial antimicrobial resistance detected. The predominant serotypes circulating in the community are covered by available PCVs. Inclusion of PCV into the country's National Immunisation Program at the earliest opportunity will have a large impact on childhood disease. Funding Gavi, the Vaccine Alliance, and Australia's Department of Foreign Affairs and Trade (DFAT) provided funding support for this project.