A major Phase 3 clinical trial conducted in India has delivered important new data on two experimental tuberculosis vaccines, confirming their strong safety profiles while highlighting the ongoing challenge of achieving comprehensive protection against all forms of the disease. The PreVenTB study, published in The BMJ on April 9, 2026, evaluated VPM1002 and Immuvac among thousands of healthy household contacts of people with smear-positive pulmonary TB, offering fresh insights into next-generation options to combat one of the world’s deadliest infectious diseases.
Both vaccines were found to be well-tolerated across adults and children, with only mild local reactions such as injection-site soreness reported in roughly one-third of participants. No serious vaccine-related adverse events emerged during the trial, and both candidates successfully triggered measurable immune responses against Mycobacterium tuberculosis. These safety results represent a positive step forward, especially in a high-burden country like India, where TB continues to claim hundreds of thousands of lives annually and where any new preventive tool must meet rigorous tolerability standards for widespread use.
However, the vaccines fell short of demonstrating broad efficacy. Neither VPM1002 nor Immuvac significantly reduced the overall incidence of microbiologically confirmed TB or pulmonary TB, the most common and transmissible form of the disease. Researchers noted that the COVID-19 pandemic disrupted follow-up schedules and caused some participants to miss the second dose, which may have influenced certain outcomes. Despite these limitations, the trial revealed a promising signal in a specific subgroup: participants with positive tuberculin skin tests showed approximately 65% efficacy against extrapulmonary TB, a less common but often more severe manifestation that affects organs outside the lungs.
VPM1002 is a genetically modified version of the century-old BCG vaccine, engineered to improve safety and immunogenicity by incorporating elements from Listeria monocytogenes. Immuvac, also known as MIP, is based on a heat-killed Mycobacterium indicus pranii formulation originally developed as an immunomodulator. Both represent innovative approaches aimed at overcoming the variable and often limited protection provided by BCG, particularly in adolescents and adults where most TB transmission occurs.
The findings underscore the complexity of TB vaccine development. While the current BCG vaccine offers strong protection against severe forms of TB in young children, its effectiveness wanes in older populations and against pulmonary disease. The PreVenTB results add to a growing body of evidence that new candidates must be carefully tailored to different age groups, infection statuses, and disease presentations. Experts emphasize that even partial protection against extrapulmonary forms could still deliver meaningful public health benefits in high-risk settings.
This Indian trial, sponsored by the Indian Council of Medical Research and involving multiple collaborating institutions, stands as one of the largest recent evaluations of novel TB vaccines in a real-world endemic context. Although the primary efficacy endpoints for all forms of TB were not met, the confirmed safety and immunogenicity data will help guide further refinements and larger or targeted studies. Ongoing global efforts, including advanced trials of other candidates like M72/AS01E, continue to build momentum toward a more effective arsenal against TB.
For now, the results send a clear message: progress in TB prevention is incremental but steady. Safe, immunogenic vaccines that offer targeted benefits represent valuable building blocks. As researchers analyze subgroup data and explore combination strategies or improved formulations, these two candidates provide valuable lessons that could accelerate the next wave of innovation. With TB remaining a global emergency that disproportionately affects low- and middle-income countries, every piece of reliable clinical evidence brings the world closer to vaccines capable of turning the tide against this persistent pathogen.