Adverse events occurred more often in the BCG revaccination group, and most were due to injection-site reactions
By Elana Gotkine HealthDay Reporter
MONDAY, May 12, 2025 (HealthDay News) — Bacille Calmette-Guérin (BCG) revaccination is not efficacious for preventing sustained Mycobacterium tuberculosis infection, defined by sustained QuantiFERON-TB (QFT) test conversion, according to a study published in the May 8 issue of the New England Journal of Medicine.
Alexander C. Schmidt, M.D., from the Gates Medical Research Institute in Cambridge, Massachusetts, and colleagues conducted a phase 2b, double-blind, randomized trial to examine the efficacy of BCG revaccination compared with placebo for the prevention of sustained QFT test conversion in QFT test-negative HIV-negative adolescents. A secondary analysis assessed adverse events, while immunogenicity was assessed in an exploratory analysis. The trial included 1,836 participants: 918 were randomly allocated to receive the BCG vaccine and 917 to receive placebo.
The researchers observed a sustained QFT conversion in 62 of 871 and 59 of 849 participants in the BCG-vaccine and placebo groups, respectively, after 30 months, with a hazard ratio of 1.04 (95 percent confidence interval, 0.73 to 1.48) and vaccine efficacy point estimate of −3.8 percent (95 percent confidence interval, −48.3 to 27.4). Compared with the placebo group, adverse events occurred more often in the BCG-vaccine group, and most were due to injection-site reactions. Cytokine-positive type 1 helper CD4 T cells were induced by BCG revaccination.
“Although this trial does not allow us to draw firm conclusions on the efficacy of BCG revaccination for the prevention of disease, the lack of vaccine efficacy with respect to prevention of infection probably decreases the likelihood of BCG revaccination conferring protection against disease,” the authors write.
Several authors disclosed ties to the pharmaceutical and other industries; one author holds related patents.
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