The search for a modern replacement for the century-old BCG vaccine has hit a significant hurdle. Results from a major Phase 3 clinical trial in India indicate that two highly anticipated recent TB vaccine candidates in Indian clinical trials, VPM1002 and Immuvac, failed to provide broad, statistically significant protection against the most common forms of tuberculosis.
The PreVenTB trial, which tracked thousands of healthy household contacts of patients with smear-positive TB, found that neither candidate significantly lowered the overall incidence of pulmonary TB—the most infectious form of the disease. The findings, published in The BMJ on April 9, 2026, underscore the persistent difficulty scientists face in inducing long-term, sterilizing immunity against Mycobacterium tuberculosis.
Despite the overall disappointment, the data revealed a critical “silver lining” for specific populations. Even as the vaccines struggled to prevent pulmonary disease in the general adult cohort, one candidate showed a surprising degree of efficacy in children and against less common, non-pulmonary infections.
Mixed Results: Pulmonary Failure vs. Extrapulmonary Hope
The primary goal of the PreVenTB trial was to determine if these next-generation vaccines could outperform the current standard of care. Although, the numbers for VPM1002 were modest: it demonstrated an efficacy of 21.4% against all forms of TB and 19.5% against pulmonary TB, neither of which reached statistical significance.
The results for Immuvac were similarly limited, particularly regarding its ability to prevent the progression of the disease in the lungs. However, the trial shifted the conversation toward extrapulmonary TB—infections that occur outside the lungs, such as in the lymph nodes, kidneys, or spine.
In this specific category, VPM1002 showed a more promising efficacy of 50.4% (95% confidence interval of 0.8% to 75.2%). Immuvac also showed a 33.2% efficacy against extrapulmonary TB, though this result was not statistically significant. These findings suggest that while the vaccines may not stop the primary respiratory infection, they might help the body contain the bacteria and prevent it from spreading to other organs.
| Metric | VPM1002 Efficacy | Immuvac Efficacy |
|---|---|---|
| Overall TB Protection | 21.4% (Not Significant) | Not Specified |
| Pulmonary TB | 19.5% (Not Significant) | Not Significant |
| Extrapulmonary TB | 50.4% | 33.2% (Not Significant) |
| Children (6–14 yrs) | 64.6% (Overall) | Not Specified |
A Breakthrough for Pediatric Protection
For physicians, the most compelling data emerged from a post-hoc analysis of younger participants. In children aged 6 to 14 years, VPM1002 performed remarkably better, showing 64.6% efficacy against all forms of the disease. This suggests that the vaccine may be far more effective when administered during specific developmental windows of the immune system.
Further analysis showed that both vaccines performed better in participants who already had positive tuberculin skin tests, achieving approximately 65% efficacy against extrapulmonary TB in that group. Biologically, the vaccines succeeded in inducing specific immune responses, specifically the production of polyfunctional CD4+ T cells, which are essential for fighting intracellular pathogens.
However, a critical gap remains: neither vaccine was able to prevent latent TB infection. Which means that while the vaccines might reduce the risk of the disease becoming “active,” they do not stop the bacteria from establishing a dormant presence in the body.
The Global Reliance on BCG
These results highlight the precarious position of global public health, as the BCG vaccine remains the only licensed TB vaccine worldwide. Developed over a century ago, BCG is routinely administered in approximately 156 of 194 countries with moderate-to-high TB incidence. In 2023 alone, an estimated 323 million BCG doses were administered, primarily to newborns to prevent severe childhood forms of the disease.
The global landscape of BCG is fragmented, with various strains—including the Danish 1331, Bulgarian SL-222, Russian, and Tokyo 172-1—used across different regions. The Danish strain remains the most widely deployed globally.
In the United States, the approach is different. Because TB incidence is low, BCG is not part of the routine immunization schedule. It is reserved for high-risk individuals, such as healthcare workers or travelers visiting endemic areas. Interestingly, the medical community has recently pivoted toward using the BCG vaccine in various experimental cancer treatments, leveraging its ability to modulate the immune system.
TB Trends in the United States
While the focus of the PreVenTB trial was in India, the broader context of the disease remains relevant in the U.S. According to provisional data from the CDC, U.S. Tuberculosis cases saw a sharp decline in 2020, followed by a steady rebound between 2021 and 2024. While there was a slight decline reported in 2025, the U.S. Incidence rate remains among the lowest globally, though the recent uptick serves as a reminder that the disease is never fully eradicated.
Looking Ahead: The Path to a New Vaccine
The PreVenTB trial, funded by the Indian Council of Medical Research (ICMR) and registered as CTRI/2019/01/017026, provides a sobering reminder of the complexity of the TB bacterium. The fact that VPM1002 showed meaningful efficacy in children and against extrapulmonary TB suggests that a “one-size-fits-all” vaccine may not be the answer. Instead, the future may lie in age-specific boosters or combination vaccines.
The immediate next step for researchers will be to analyze why the pediatric response was so robust and whether the vaccine’s ability to prevent extrapulmonary spread can be leveraged into a broader clinical tool. Public health officials will continue to monitor the ICMR’s subsequent analyses to determine if a modified version of these candidates could eventually reach licensure.
Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.
Do you think the focus of TB research should shift toward pediatric-specific vaccines? Share your thoughts in the comments or share this story with your network.
Worth a look
