New TB Vaccine Trials: Progress in the Fight Against Tuberculosis
Tuberculosis (TB) remains one of the most lethal infectious diseases globally, claiming 1.4 million lives annually. While the BCG vaccine has long been the primary tool for prevention, its effectiveness is largely limited to severe forms of TB in young children, leaving adolescents and adults vulnerable. Recent clinical trials and research breakthroughs are now aiming to fill this gap with new vaccine candidates designed to protect a broader population and treat existing infections.
- A large trial in India tested two new vaccines, VPM1002 and Immuvac, finding them safe for adults and children.
- VPM1002 demonstrated 50.4% effectiveness against extrapulmonary TB (EPTB), rising to 79.5% in adults aged 36-60.
- Researchers at Johns Hopkins have developed a therapeutic intranasal DNA vaccine to target drug-tolerant “persister” bacteria.
- New vaccines focus on preventing the progression from latent to active TB, as neither VPM1002 nor Immuvac prevented latent infection.
Evaluating VPM1002 and Immuvac: Results from India
To address the limitations of the BCG vaccine, researchers in India conducted a comprehensive trial involving 12,717 household contacts of TB patients across six states. The study, published by The BMJ, evaluated whether the VPM1002 and Immuvac vaccines could prevent all forms of tuberculosis and latent infections.
Safety and Efficacy
The trial confirmed that both VPM1002 and Immuvac are safe for use in both adults and children. However, the results regarding efficacy were mixed. Neither vaccine provided general protection against all forms of TB or prevented the initial development of latent (dormant) TB infections.
Success in Preventing Active TB
Despite the lack of general protection, both vaccines showed a critical ability to prevent the progression from latent TB to active disease. Specifically, VPM1002 showed significant effectiveness against extrapulmonary TB (EPTB)—TB that affects organs other than the lungs. The vaccine’s effectiveness against EPTB was 50.4% across all age groups and reached 79.5% among participants aged 36-60.
A New Approach: The Therapeutic Nasal DNA Vaccine
While some vaccines focus on prevention, other research is targeting those already infected. A research team at Johns Hopkins Medicine has developed a therapeutic intranasal DNA vaccine. This vaccine is designed to be used alongside standard drug therapies to improve patient outcomes.
The primary goal of this DNA fusion vaccine is to direct the immune system to fight “persisters”—drug-tolerant bacteria that survive prolonged antibiotic treatment and often cause the disease to relapse. In studies involving mice, this vaccine helped clear bacteria faster, reduced lung inflammation, and prevented relapse after treatment ended.
The Global Burden of Tuberculosis
The urgency for these medical breakthroughs is driven by the scale of the TB epidemic. According to the World Health Organization (WHO), approximately 2 billion people—about one-quarter of the world’s population—have a latent, symptom-free TB infection. In 2024, more than 10 million people developed active TB disease, resulting in 1.2 million deaths.
The challenge is further compounded by several factors:
- Drug Resistance: The emergence of drug-resistant strains makes traditional treatment more difficult.
- Treatment Complexity: Long multidrug courses are often hard for patients to complete.
- Comorbidities: In low and middle-income countries, the burden is increased by malnutrition and HIV infection.
Frequently Asked Questions
What is the difference between pulmonary and extrapulmonary TB?
Pulmonary TB (PTB) primarily affects the lungs and is the most common form of the disease. Extrapulmonary TB (EPTB) occurs when the bacteria spread to other parts of the body, such as the lymph nodes, kidneys, or spine.
Can these new vaccines replace the BCG vaccine?
Currently, BCG remains the only licensed TB vaccine. The new candidates like VPM1002 are being tested to fill gaps where BCG is ineffective, particularly for adults and in preventing the progression to active disease.
What is a latent TB infection?
A latent infection is a state where the TB bacteria remain in the body but are dormant. The person has no symptoms and cannot spread the disease to others, but the infection can turn into “active” if the immune system weakens.
Looking Ahead
The shift toward therapeutic vaccines and targeted protection against extrapulmonary TB represents a significant step forward. By combining traditional drug therapies with new immunological tools, health professionals aim to shorten treatment regimens and finally reduce the global mortality rate of this ancient disease.