India, facing a high TB burden, is considering BCG revaccination for adults and elderly as a cost-effective strategy. Although the long-term Chingleput trial showed minimal benefit in adults and only marginal gains in children, updated models suggest potential reductions in TB cases and deaths with revaccination, especially in high-risk groups. Existing vaccination infrastructure lowers implementation costs, making it a pragmatic interim approach while new, more effective TB vaccines are developed. However, real-world impact remains modest, and careful evaluation alongside emerging vaccine options is essential.
Being a tuberculosis researcher, I could not prevent myself but add few important lines. Tuberculosis differs from other infections to great extent. The ubiquitous enzymes superoxide dismutase, glutamine synthetase, having no leader peptides, are secreted extracellularly by mycobacteria and also siderophores, the iron chelating exochelins,which play havoc in pathogenesis of tuberculosis. Also,mycobactetia has effect on iron transporters, hepcidine and slso immune system. To develop effective vaccine we are to do extensive research on those. BCG vaccination for new born is only to prevent complications of tuberculosis. I request researchers to go through my published papers on tuberculosis and to put valuable critical views on it.
Although large-scale studies—most notably the Chingleput trial—did not demonstrate significant protection from BCG revaccination in adults, recent mathematical modeling and cost-effectiveness analyses suggest that targeted revaccination could yield moderate public health benefits. Specifically, in high-risk groups and settings with established immunization infrastructure, BCG revaccination may serve as a pragmatic and economically viable interim measure while novel vaccine candidates with improved efficacy undergo clinical validation.
Nonetheless, the biological complexity of Mycobacterium tuberculosis remains a formidable challenge to vaccine development. The pathogen exhibits sophisticated mechanisms of immune evasion and persistence, including the secretion of leaderless enzymes (e.g., superoxide dismutase, glutamine synthetase) and iron-chelating siderophores such as exochelins. These molecular features underscore its capacity to modulate host iron metabolism (e.g., via hepcidin dysregulation) and dampen protective immune responses.
Given these factors, any vaccination strategy—particularly revaccination of adults—should be grounded in a mechanistic understanding of host-pathogen interactions, and integrated with broader public health measures such as latent TB screening, treatment adherence programs, and the development of biomarkers for protective immunity.
While BCG remains essential for preventing severe forms of childhood TB, its role in adult protection is limited and variable across epidemiological contexts. Therefore, decisions on BCG revaccination policies should be informed by region-specific evidence, implementation capacity, and emerging data from controlled trials.
I welcome further discussion and interdisciplinary collaboration to refine our collective approach to TB vaccine strategy.
Tuberculosis is a global public health problem. Everybody acknowledges it. But there is always lacklustural response how to fight and eradicate it. All are to discuss openheartedly, specially those who have infrastructure resources to do research to fight this menace. Pl join the discussion and do the needful.I am regularly putting questions on this regard, but no taker in real numbers.
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