Two new TB vaccine candidates show promise but fail to stop infection
A large trial in India suggests the VPM1002 and Immuvac vaccine candidates are safe and may reduce the risk of active tuberculosis in adults and older children, but do not prevent infection or transmission.
- 14 April 2026
- 6 min read
- by Linda Geddes
At a glance
- Two experimental TB vaccines, VPM1002 and Immuvac, were found to be safe in a large trial of more than 12,000 people in India. Both vaccines also appeared to reduce progression from latent (dormant) infection to active TB.
- Neither vaccine prevented infection nor protected against all forms of TB – especially pulmonary TB, the form that drives transmission. But VPM1002 reduced the risk of developing extrapulmonary TB by about half, compared to the control group.
- These are just two of at least 20 new TB vaccines in development, with other candidates showing more promise in preventing infection.
Two experimental tuberculosis vaccines have shown some protective effects in a large clinical trial, but their failure to prevent infection or the most infectious form of TB highlights the ongoing challenge of controlling the world’s deadliest infectious disease.
The vaccines – one a modified version of the century-old Bacillus Calmette–Guérin (BCG) vaccine and the other a killed bacterial vaccine – were found to be safe and to reduce the risk of active disease in people with latent (dormant) tuberculosis, but did not prevent infection or fully protect against pulmonary TB, which affects the lungs and drives transmission.
The good news is that other new candidates, such as the M72/AS01 and MTBVAC vaccines, are also progressing through trials and have shown promising results in preventing active pulmonary TB, raising hopes for effective vaccines for adolescents and adults in the future.
How significant a problem is TB?
Tuberculosis is the world’s biggest infectious killer, claiming an estimated 1.2 million lives in 2024 alone – more than two lives every minute.
Growing resistance to antibiotics is making it harder to treat, and while the BCG vaccine provides significant protection against TB disease in infants and young children, this wanes as they get older, and it provides only limited protection for adolescents or adults, who account for the bulk of TB infections and disease transmission today.
The good news is that other new candidates, such as the M72/AS01 and MTBVAC vaccines, are also progressing through trials and have shown promising results in preventing active pulmonary TB.
The BCG vaccine is also relatively poor at preventing tuberculosis infection and provides inconsistent protection against latent infection (where the bacterium lies contained and dormant in the body for many years) from progressing to active disease, particularly in adolescents and adults.
Because of this, new vaccines that prevent TB disease in adolescents and adults are urgently needed.
What new TB vaccine candidates are being developed?
There are currently at least 20 tuberculosis vaccine candidates for adults and adolescents in the clinical pipeline. Two of these, VPM1002 and Immuvac, were the subject of this latest clinical trial.
The VPM1002 vaccine uses the same weakened bacterium (Mycobacterium bovis) as the BCG vaccine, but it has been genetically modified to improve how it interacts with immune cells, with the goal of triggering a stronger, more effective immune response, especially in adults.
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Immuvac is made from a killed bacterium called Mycobacterium indicus pranii, and is designed to boost the immune system more broadly, helping it to respond better to infections such as TB and leprosy.
How safe and effective are these potential TB vaccines?
The new study, which was published in the British Medical Journal, evaluated whether VPM1002 and Immuvac could generate an immune response against tuberculosis bacteria, protect against pulmonary (affecting the lungs) and extrapulmonary (affecting other parts of the body) forms of the disease, or prevent latent infection.
Researchers enrolled 12,717 household contacts (aged six years and older) of recently diagnosed TB patients in six Indian states between July 2019 and December 2020, including those with pre-existing conditions like diabetes and risk factors for severe disease.
Although neither vaccine provided protection against all forms of tuberculosis nor prevented latent infection, both helped to prevent the progression to active disease in those who developed latent infections, and both appeared to be safe.
This is important because these groups are more likely to develop active TB, making the findings more representative of real-world populations and allowing researchers to assess how well the vaccines perform in those at highest risk.
Participants were randomly allocated to receive a first dose of either VPM1002, Immuvac or a placebo, with 11,829 of them also receiving a second dose one month later. They were followed up for 38 months, to assess outcomes.
What did the study find?
Although neither vaccine provided protection against all forms of tuberculosis nor prevented latent infection, both helped to prevent the progression to active disease in those who developed latent infections, and both appeared to be safe.
VPM1002 also showed 50.4% effectiveness against extrapulmonary TB across all age groups, meaning it reduced the risk of developing this form of the disease by about half, compared to the control group, with higher effectiveness (79.5%) observed in individuals aged 36–60 years.
These findings suggest a potentially significant public health benefit, as extrapulmonary TB is often associated with a higher risk of death than pulmonary TB.
Another potentially promising finding was that both vaccines showed protective effects in children, with VPM1002 reducing the risk of developing active tuberculosis in those aged 6 to 14 years, and Immuvac providing protection against extrapulmonary disease in children aged 6 to 10.
However, the exact level of protection in these age groups is less certain, as fewer TB cases were observed in these groups.
Also, neither vaccine protected children and adults who were underweight, suggesting that nutritional support may be needed alongside vaccination, especially for younger children, the authors said.
What do the results of this study mean for TB prevention programmes?
Although these vaccine candidates showed some protective effects, they did not provide significant protection against all forms of tuberculosis, particularly pulmonary TB, and did not protect against infection.
This suggests the vaccines are unlikely to be prioritised for large-scale roll-out in adolescent or adult TB vaccination programmes, although they could still have a role in targeted settings, such as among household contacts of TB patients.
Other new candidates, such as the M72/AS01 and MTBVAC vaccines, are also progressing through trials, with more promising results in preventing the disease. M72/AS01E is a protein-based vaccine, designed to boost the immune response against Mycobacterium tuberculosis. In a phase 2b trial, it reduced the risk of developing active pulmonary TB by around 50% in adults who were already thought to have been infected with the bacterium, and is currently being tested in a large phase 3 study.
MTBVAC is a live attenuated vaccine derived from M. tuberculosis, currently being evaluated in phase 3 trials in newborns in several sub-Saharan African countries. A large phase 2b trial in adolescents and adults has recently begun in Africa, with a phase 3 trial in this group considered in India.
Though modest, the latest results highlight both the sustained progress being made, and how far there is still to go in the fight against the world’s deadliest infectious disease.
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