Bharat Biotech’s TB Vaccine Faces Regulatory Review Ahead of Phase III Trial
Bharat Biotech’s ambitious effort to advance its novel tuberculosis (TB) vaccine candidate, MTBVAC (BBV169), into Phase III clinical trials has encountered a regulatory hurdle. The Central Drugs Standard Control Organization (CDSCO), through its Subject Expert Committee (SEC) on Vaccines, has requested additional clinical data and protocol modifications before granting approval for the next stage of development.
The matter was discussed during the SEC (Vaccine) meeting held on May 28, 2026, where Bharat Biotech presented its proposed Phase III clinical trial protocol alongside an interim report from its ongoing Phase II study.
About MTBVAC (BBV169)
MTBVAC is a live attenuated Mycobacterium tuberculosis vaccine being developed as a potential alternative or improvement to the currently used Bacillus Calmette-Guérin (BCG) vaccine.
The vaccine is designed to provide enhanced protection against tuberculosis, one of the world’s deadliest infectious diseases. India, which bears a significant share of the global TB burden, could greatly benefit from more effective preventive tools.
Proposed Phase III Clinical Trial
Bharat Biotech proposed a:
- Randomized study
- Double-blind design
- Placebo-controlled trial
- Multicentre clinical study
The Phase III trial aims to evaluate:
- Vaccine efficacy
- Safety profile
- Immunogenicity
- Prevention of active tuberculosis disease
The study is intended for Indian adolescents and adults, representing a critical population in the country’s TB control strategy.
Encouraging Findings from Phase II Study
According to the interim Phase II clinical study report submitted by Bharat Biotech:
- Safety data up to 90 days were provided.
- Immunogenicity data up to 56 days were presented.
- MTBVAC generated immune responses comparable to the currently used BCG vaccine.
- Positive results were observed in both:
- QuantiFERON-TB (QFT) negative participants
- QuantiFERON-TB (QFT) positive participants
These findings suggest that the vaccine candidate has the potential to induce a robust immune response against tuberculosis infection.
Key Concerns Raised by the Subject Expert Committee
Despite the encouraging preliminary results, the SEC identified several gaps that need to be addressed before Phase III approval can be considered.
1. Missing Detailed Immunogenicity Data
The committee noted that detailed immunogenicity results for MTBVAC at:
- Day 0
- Day 28
- Day 56
were not adequately submitted.
Experts emphasized that these data are essential to reconfirm the primary objectives of the ongoing Phase II study and to better understand vaccine-induced immune responses over time.
2. Lack of Age-Stratified Analysis
The approved protocol required separate analyses for:
- Adolescents
- Adults
However, the submitted interim report did not include age-specific evaluations.
The SEC requested detailed stratified analyses to determine whether vaccine performance differs across age groups.
3. Verification of Cell-Mediated Immune Response Data
The committee also sought clarification regarding:
- Graphical presentations of cell-mediated immune responses
- Responder-rate analyses from Phase I studies
Experts recommended re-verification of these findings and asked the company to provide raw subject-level data to support the presented results.
Serious Adverse Event Raises Additional Questions
Another important issue discussed during the review involved a reported Serious Adverse Event (SAE).
To determine whether the event was linked to:
- A naturally occurring tuberculosis infection, or
- A vaccine-derived strain,
the SEC recommended conducting detailed genomic analysis.
The outcome of this investigation will be critical in establishing the safety profile of MTBVAC before large-scale human testing proceeds.
Why This Matters
Tuberculosis remains one of India’s most pressing public health challenges. While the BCG vaccine has been used for decades, its effectiveness against pulmonary TB in adolescents and adults varies significantly.
A successful vaccine such as MTBVAC could:
- Improve TB prevention
- Reduce disease transmission
- Support India’s National TB Elimination Programme
- Contribute to global TB eradication efforts
However, regulatory authorities are ensuring that comprehensive safety and efficacy evidence is available before allowing large-scale Phase III testing.
What Happens Next?
Bharat Biotech will now need to:
- Submit detailed immunogenicity datasets.
- Provide age-stratified analyses for adolescents and adults.
- Revalidate Phase I immune-response findings with raw participant-level data.
- Complete genomic investigations related to the reported serious adverse event.
- Revise the Phase III protocol as recommended by the SEC.
Only after satisfactory review of the additional information will CDSCO consider granting approval for the Phase III clinical trial.
Conclusion
The SEC’s decision does not represent a rejection of MTBVAC but rather a request for stronger supporting evidence before advancing to large-scale efficacy testing. While interim Phase II results indicate promising immunogenicity comparable to BCG, regulators are seeking greater clarity on safety, age-specific responses, and immune-response data integrity.
As tuberculosis continues to pose a major health challenge in India, the progress of MTBVAC remains closely watched by researchers, healthcare professionals, and public health authorities alike. The coming months will be crucial in determining whether Bharat Biotech’s vaccine candidate can successfully move into Phase III development and potentially become a next-generation tool in the fight against TB.
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