TB Vaccine: Current Scenario and Future Possibilities

Tuberculosis (TB) caused by Mycobacterium tuberculosis has been a major global health challenge for a very long time, especially in low-income countries. It affects more than 10 million people annually and has caused about 1.25 billion deaths in 2023. Bacille Calmette-Guerin (BCG) has been the only vaccine used for the last century. Still, its effectiveness varies widely, particularly in protecting adults and adolescents from the Pulmonary form of TB, necessitating the importance of better and improved vaccines. The emergence of drug-resistant TB, like MDR-TB (multidrug-resistant TB and XDR-TB (extensively drug-resistant TB, has made the situation even more serious. Nearly nineteen new TB vaccines are in clinical trials, with several already in phase 3 trials. MTBVAC is a live attenuated vaccine derived from M. tuberculosis by deletions of phoP and fadD26 virulence genes. This vaccine has shown better immunogenicity and safety and is currently being tested in HIV-negative infants in Sub-Saharan Africa. Recombinant BCG vaccine VPM1002, which expresses listeriolysin O, has shown superior protection and immune response in preclinical studies and is in Phase 3 trials. A subunit vaccine, GamTBvac, combining Ag85A and ESAT-6/CFP-10 antigens with a dextran/CpG adjuvant, has shown strong Th1 and humoral responses. Currently, this vaccine is in Phase 3 trials. With the use of Mycobacterium indicus pranii and Mycobacterium vaccae, the effectiveness of chemotherapy could be increased manifold, thus proving itself to be a potential candidate for tuberculosis. All these developments thus highlight the need for increasing the funding, commitment, and human resources for the production of the TB vaccine, which could help control TB in high-risk regions of the world.