India continues to face a staggering public health challenge, currently bearing the world’s highest burden of tuberculosis (TB), accounting for approximately 27% of global cases. In a significant attempt to bridge the gap in prevention, two new vaccines have shown promise in tackling TB, especially among kids and high-risk populations, according to a study published in the British Medical Journal (BMJ) on April 9.
The research focuses on two candidates: VPM1002, a genetically modified recombinant Bacillus Calmette-Guérin (BCG) vaccine developed by the Serum Institute of India in Pune and Immuvac, manufactured by Cadila Pharmaceuticals Ltd. Even as the traditional BCG vaccine remains the only licensed option globally, its efficacy is largely limited to preventing severe forms of the disease in very young infants, leaving adolescents and adults vulnerable.
These new developments target a critical blind spot in current TB prevention: the transition from latent infection to active disease. The study, led by researchers including Manjula Singh of the Indian Council of Medical Research and Randeep Guleria, suggests that these vaccines could significantly reduce the morbidity associated with extrapulmonary TB (EPTB), a form of the disease that is notoriously tricky to diagnose, and treat.
Addressing the Challenge of Extrapulmonary TB
Tuberculosis is most commonly associated with the lungs, but extrapulmonary TB occurs when the bacteria spread to other organs, such as the lymph nodes, pleura, abdomen, and spine. In India, EPTB accounts for roughly 22% of all reported TB cases. This variant of the disease is particularly dangerous because it is “paucibacillary,” meaning there are very few bacteria present in the samples, often making it invisible to standard diagnostic tools, including advanced tests like Xpert MTB/RIF.
The BMJ study indicates that both VPM1002 and Immuvac are safe and provide substantial protection against this specific form of the disease. VPM1002 demonstrated a 50.4% effectiveness against EPTB across all age groups. The efficacy was even more pronounced in older adults, with those aged 36 to 60 years showing a 79.5% effectiveness rate.
For those already living with a latent TB infection—where the bacteria remain dormant in the body—the vaccines showed a protective efficacy of over 65% against the progression to EPTB, specifically 64.9% for VPM1002 and 66.3% for Immuvac.
Comparative Efficacy by Age and Condition
| Vaccine | Target Group | Efficacy (EPTB/All TB) | Key Finding |
|---|---|---|---|
| VPM1002 | Children (6-14 years) | >60% | Protects against PTB and EPTB |
| Immuvac | Children (6-10 years) | >60% | Protective against EPTB only |
| VPM1002 | Adults (36-60 years) | 79.5% | High effectiveness against EPTB |
| Both | Latent TB Patients | >65% | Prevents progression to EPTB |
A Critical Shield for Children and Adolescents
One of the most encouraging aspects of the research is the protective efficacy seen in younger populations. For children and adolescents aged 6 to 14, VPM1002 showed over 60% protective efficacy against all forms of TB, including both pulmonary TB (PTB) and extrapulmonary TB. Immuvac similarly provided over 60% efficacy against EPTB in children between 6 and 10 years old.
This is a vital breakthrough because the current standard BCG vaccine does not offer reliable protection for adolescents. By providing a shield for those in the 6-to-14 age bracket, these vaccines could potentially break the cycle of transmission within households, particularly for those who are close contacts of patients with sputum-positive TB.
However, the researchers noted a significant limitation: neither vaccine provided protection for underweight children or adults. This suggests that the biological response to the vaccine is closely tied to the patient’s overall health and nutritional status.
The Intersection of Medicine and Social Determinants
The finding that malnutrition hinders vaccine efficacy highlights a recurring theme in public health: medicine alone cannot solve a crisis rooted in socioeconomic conditions. Dr. Anant Phadke, a public healthcare advocate, noted that while the vaccines are a useful tool in the broader strategy to eliminate TB in India, they are not a silver bullet.
Phadke pointed out that the vaccines provide protection to approximately 50% of children aged 5 to 18 who are not malnourished and are household contacts of infected patients. He emphasized that improving nutrition and housing must remain the mainstay of TB control and elimination efforts, as a vaccine cannot compensate for a lack of basic caloric and nutritional needs.
It is also important to clarify the scope of these vaccines. The study found that neither VPM1002 nor Immuvac prevented the initial latent TB infection, nor did they show efficacy against all forms of microbiologically confirmed pulmonary TB. Instead, their primary value lies in preventing the progression from a latent state to active, symptomatic disease.
Disclaimer: This article is for informational purposes only and does not constitute medical advice. Please consult a healthcare provider for diagnosis and treatment options regarding tuberculosis.
The next phase for these candidates will involve further analysis of the BMJ data to determine how they can be integrated into India’s National Tuberculosis Elimination Program. Public health officials will likely focus on how to pair these vaccinations with nutritional support programs to maximize efficacy in vulnerable populations.
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