Effectiveness of Bacillus Calmette-Guerin for Tuberculosis Prevention Among Chinese People: Systematic Review and Meta-analysis

Background: Our previous study showed that the protective effect of Bacillus Calmette-Guerin (BCG) declined with time, which is supported by a following study saying "BCG vaccination protection against tuberculosis varies between populations, to an extent that cannot be attributed to chance alone". Objective: To investigate BCG protective effect among Chinese people, so as to update the development and use of immunological agents. Methods: Systematic review was carried out: electronic databases searches, screening of identified studies based on inclusion and exclusion criteria, data extraction and meta-analysis were undertaken. Results: Initial search identified 3067 articles from four Chinese databases, after selection, 25 met the eligibility criteria among which 6 were cohort studies and 19 were casecontrol studies, with the total participant of 1311758 and 5169 respectively. None of the experimental studies such as randomized controlled trials (RCTs) were identified. The P value of Egger's test was 0.016 for cohort studies and 0.067 for case-control studies, which, together with funnel plot, indicated that the available evidences were at risk of publication bias. The pooled estimate of RR for cohort studies was 0.24, with 95% confidence interval (95%CI) (0.11, 0.52), and of OR for case-control studies it was 0.37 with 95%CI (0.31,0.45). Conclusions: The available evidence shows positive and definite effect of BCG in preventing TB among Chinese people but it should be supported by more studies to avoid publication bias risk. High quality studies are encouraged worldwide to update the development and use of immunological agents to cope with tuberculosis epidemiology.