Efficacy of Bacillus Calmette-Guérin revaccination in preventing tuberculosis disease: a systematic review and meta-analysis

Background There is no consensus on the efficacy of Bacillus Calmette-Guérin (BCG) revaccination. Because of this, we aimed to compare the effect of BCG revaccination with no revaccination in preventing tuberculosis (TB) disease. Methods We searched PubMed, Embase, and the Cochrane Library databases from inception to December of 2023 for studies that compared BCG revaccination with no revaccination or placebo for this systematic review and meta-analysis. Outcomes of interest were incidence of TB disease, pulmonary TB and extrapulmonary TB. We pooled odds ratios (ORs) with 95% confidence interval (CI) using a random-effects model in R statistical software version 4.3.1. Heterogeneity was assessed with I2 statistics. Results Five studies, involving 1 012 007 patients, of whom 501 597 (49.56%) were revaccinated with BCG, were included in the meta-analysis. There was a benefit in tuberculosis disease incidence in patients who received revaccination compared to patients who did not (OR 0.89; 95% CI: 0.81-0.98; P = .019; I2 = 53%) in the randomized controlled trials. When including observational studies, we found the same trend (OR 0.90; 95% CI: 0.77-1.05; P = .124; I2 = 26%) as well as in preventing against both extrapulmonary (OR 0.82; 95% CI: 0.38-1.76; P = .375; I2 = 24%) and pulmonary (OR 0.93; 95% CI: 0.86-1.01; P = .062; I2 = 0%) cases. Conclusions BCG revaccination was associated with a slight decrease in the incidence of tuberculosis, pulmonary tuberculosis, and extrapulmonary tuberculosis.