Tuberculosis

Tuberculosis

Context

Recent data from the Indian Council of Medical Research’s (ICMR) landmark PreVenTB Phase III clinical trial has revealed that two newly evaluated indigenous vaccines, VPM1002 and Immuvac, provide significant protection against extrapulmonary tuberculosis (EPTB).

About the News

What Is Tuberculosis (TB)? Tuberculosis is a chronic, highly infectious bacterial disease caused by the pathogen Mycobacterium tuberculosis. It primarily spreads through the air via respiratory droplets when an individual with an active infection coughs or sneezes. While the immune system can hold the bacteria in an asymptomatic, latent state for years, the infection can progress into active, destructive disease pathways.

The Two Primary Manifestations of TB:

• Pulmonary Tuberculosis (PTB): The most common and infectious form of the disease, which directly attacks the lungs. Because it causes severe coughing, it is the primary engine driving airborne transmission across communities.
• Extrapulmonary Tuberculosis (EPTB): A hidden, debilitating manifestation where the bacterial infection migrates beyond the lungs to infect other vital organs (such as the lymph nodes, spine, brain, or kidneys). EPTB is significantly harder to diagnose, is frequently missed by standard screenings, and causes severe morbidity.

Current Global and National Status of TB:

• The Leading Infectious Killer: Tuberculosis remains one of the world’s oldest and most lethal epidemics, killing more people annually than any other infectious disease—even surpassing the peak fatality rates of the COVID-19 pandemic.
• High Burden in Low- and Middle-Income Countries (LMICs): In developing economies, the baseline incidence of TB remains stubbornly high, hovering between 200 and 300 cases per 100,000 population.
• The Elimination Threshold Gap: To formally declare the elimination of TB, public health bodies must reduce incidence rates to just 10–20 cases per 100,000 population, a target requiring massive public health investments.
• A Stagnant Vaccine Landscape: Despite over a century passing since the introduction of the initial infant BCG vaccine, there is still no universally effective commercial TB vaccine tailored for adolescents and adults.

Challenges in Eliminating Tuberculosis

• Asymmetrical Profile of Extrapulmonary TB: Because EPTB develops inside deep body tissues rather than the lungs, it escapes traditional sputum-based diagnostic tests, leading to delayed treatments and high healthcare costs.
• Uneven Distribution of Diagnostics and Preventive Therapy: Access to advanced molecular testing platforms and latent-stage preventative therapies remains deeply fragmented, allowing subclinical infections to spread unchecked.
• Widespread Malnutrition Undercutting Vaccine Efficacy: Poor nutrition and low Body Mass Index (BMI) weaken the human immune system, directly reducing the efficacy of vaccines among undernourished populations.
• Flawed One-Size-Fits-All Vaccine Expectations: Past global trials failed because they looked for a single “one-shot” silver bullet focused only on lung infections, ignoring the complex, diverse pathways of the bacterium.
• Absolute Lack of Post-Infancy Booster Strategies: India’s national immunization framework lacks any structured TB vaccination or booster guidelines for school-aged children, adolescents, or adults.

Initiatives Taken So Far

India's Domestic Framework

• National TB Elimination Programme (NTEP): A comprehensive national program designed to track cases, distribute free anti-TB drugs, and achieve elimination ahead of global timelines.
• Early Adoption of Indigenous Diagnostics: India pioneered the validation and rollout of TrueNat, an indigenous molecular test, deploying it nationwide to accelerate case detection before it even received WHO pre-qualification.
• The PreVenTB Clinical Trial: The ICMR successfully conducted a massive real-world Phase III trial across 18 sites involving 12,700 household contacts, proving that VPM1002 offers 50.4% efficacy against EPTB and 64.6% protection for children aged 6–14.

Global Frameworks

• The WHO End TB Strategy: A global framework aiming for a 90% reduction in TB deaths and an 80% reduction in incidence rates worldwide.
• UN High-Level Meetings on TB: Global political commitments focused on scaling up funding for research, closing diagnostic gaps, and delivering preventative therapy to millions with latent infections.
• Global TB Vaccine Pipeline: Ongoing international clinical networks funding trials for multi-dose, adjuvanted vaccines, though none have yet evaluated or included EPTB as a formal efficacy endpoint.

Way Forward

• Deploying Available Indigenous Vaccines Immediately: India should utilize its previous pandemic approval models to clear the single-dose VPM1002 and Immuvac vaccines for immediate use, targeting high-risk household contacts.
• Launching Targeted School-Age Booster Campaigns: Use the strong protection signals found in the PreVenTB trial to introduce a routine booster-dose strategy for children aged 6–14 years within the national immunization program.
• Integrating Direct Nutritional Supplementation with Vaccination: Scale up the Nikshay Poshan Yojana to provide dedicated nutritional support and food packages to undernourished communities, ensuring vaccines can work optimally.
• Expanding Advanced Molecular Screenings for Subclinical TB: Deploy high-resolution diagnostics and portable digital tools to catch subclinical and latent infections early, before they can progress to active, infectious pulmonary states.
• Forming a Multi-Vaccine Combination Framework: Avoid the trap of waiting for a single perfect solution by combining moderately effective tools that target different age groups and disease pathways to build a layered control system.

Conclusion

India’s bold fight against tuberculosis cannot be won by waiting for a single, perfect global breakthrough. The success of the indigenous PreVenTB trial shows that moderately effective, scalable tools like VPM1002 are ready to provide immediate protection against the hidden, lethal burden of extrapulmonary TB. Developing multi-layered, consultative public health guidelines will ensure robust implementation without relying purely on traditional, centuries-old diagnostic models.