BCG Revaccination for the Prevention of <i>Mycobacterium tuberculosis</i> Infection

BACKGROUND: release assay) from negative to positive, followed by two additional positive QFT tests at 3 and 6 months after the initial conversion (a secondary end point). A vaccine efficacy of 45% (95% confidence interval [CI], 6 to 68) was observed. METHODS: infection around the time that the vaccine or placebo was administered. Hazard ratios and 95% confidence intervals were estimated from a stratified Cox proportional-hazards model. RESULTS: A total of 1836 participants underwent randomization; 918 received the BCG vaccine, and 917 received placebo. After a median 30 months of follow-up, a sustained QFT test conversion was observed in 62 of 871 participants in the BCG-vaccine group and 59 of 849 participants in the placebo group. The hazard ratio for a sustained QFT test conversion (BCG vaccine vs. placebo) was 1.04 (95% CI, 0.73 to 1.48), for a vaccine efficacy point estimate of -3.8% (95% CI, -48.3 to 27.4). Adverse events occurred more frequently in the BCG-vaccine group than in the placebo group, and most were due to injection-site reactions (pain, redness, swelling, and ulceration). BCG revaccination induced cytokine-positive type 1 helper CD4 T cells. CONCLUSIONS: infection. (Funded by the Gates Foundation; ClinicalTrials.gov number NCT04152161.).