India TB: Can vaccines help India triumph over tuberculosis?

In 2018, India set for itself the lofty goal of eliminating pulmonary tuberculosis (TB) by 2025 - five years ahead of the deadline set by the UN's Sustainable Development Goals.

In March 2023, Prime Minister Narendra Modi reiterated this commitment at the One World TB Summit, held in the northern city of Varanasi.

But the World Health Organization's (WHO's) Global Tuberculosis Report paints a different picture - every two minutes, one person dies of the disease in India.

According to the report, India accounted for the highest global TB burden, with 27% of the 10.6 million people diagnosed with the infection in 2022. The country is also home to 47% of people who developed multi-drug resistant infection which is unresponsive or resistant to at least two of the first line of anti-TB drugs the same year.

While experts say testing and treatment remain the best-known ways to tackle the disease, India has also invested in trying to find an effective TB vaccine - since 2019, scientists have been testing two vaccines in seven research centres.

But TB vaccines are not that easy to develop.

"We don't know what exactly we want the vaccine to do. Until we have a fundamental understanding of how humans do or do not resist the tubercle bacillus [TB bacteria], it is difficult to engineer a vaccine that capitalises on that knowledge," says Dr Marcel A Behr, director of infectious diseases division at Canada's McGill University Health Centre.

Which means that so far, there is no clarity on whether a TB vaccine should induce antibodies, antigen-specific T-cells (combative cells generated by specific bacteria parts) or boost innate immunity.

Dr Behr adds that the quest for a vaccine has also been hampered because the test for TB cannot