Prevalence and serotype distribution of nasopharyngeal carriage of Streptococcus pneumoniae in China: a meta-analysis

BACKGROUND To explore the overall prevalence and serotype distribution of nasopharyngeal carriage of Streptococcus pneumoniae(S. pneumoniae) among healthy children. METHODS A search for pneumococcal nasopharyngeal carriage studies including children published up to July 31th, 2016 was conducted to describe carriage in China. The review also describes antibiotic resistance in and serotypes of S. pneumoniae and assesses the impact of vaccination on carriage in this region. Summary measures for overall prevalence, antibiotic resistance, and serotype distributions extracted from the analyzed data were determined with 95% confidence intervals (CIs) using random-effects models. Heterogeneity was assessed using I 2 test statistics. RESULTS Thirty-seven studies were included in this review, and the majority of studies (64.9%) were located in the pre-introduction period of 7-valent pneumococcal conjugate vaccine (PCV7) in China. The pooled prevalence of S. pneumoniae nasopharyngeal carriage was 21.4% (95% CI: 18.3-24.4%). Carriage was highest in children attending kindergartens [24.5%, (19.7-29.3%)] and decreased with increasing age. Before the introduction of PCV7 into China, the prevalence of S. pneumoniae nasopharyngeal carriage was 25.8% (20.7-30.9%), the pooled carriage of S. pneumoniae sharply dropped into the 14.1% (11.3-16.9%) by PCV7 vaccination period (P < 0.001). Before the pneumococcal conjugate vaccine (PCV) was introduced in China, the penicillin resistance rate in S. pneumoniae isolated from healthy children was 31.9% (21.2-42.6%); however, this rate sharply decreased after the introduction of PCV7 in China [21.6%, (7.4-35.9%)], and the difference between the rates during these two time periods was statistically significant (P value <0.05). Serotypes 19F, 6A and 23F were the most commonly isolated. Meta-analysis of data from young children showed a pooled rate estimate of 46.6% (38.8-54.4%) for PCV7 vaccine coverage and 66.2% (58.6-73.8%) for PCV13 vaccine coverage. CONCLUSIONS The prevalence of nasopharyngeal carriage among children was high in China. PCV7 immunization was found to be associated with reduction of nasopharyngeal colonization of S. pneumoniae. Conjugate vaccination coverage was slightly affected by the introduction of PCV7 into China because of low vaccination rate. The government should implement timely adjusted conjugate vaccination strategies based on our findings.