3 candidates in contention for a new TB vaccine; BCG is passé

An international TB research consortium has zeroed in upon three possible candidates for trials into a new TB vaccine.

There is already an existing vaccine – the Bacillus Calmette–Guérin (BCG) vaccine – that is a part of the immunisation programme of most TB endemic countries including India – but its efficacy is in doubt. Besides given the propensity of the TB bacteria to mutate into drug resistant forms a new vaccine is the need of the hour, felt speakers at the recently concluded First Global MInisterial Meet on Tuberculosis organised by WHO in Moscow.

Of the three molecules in contention for trials one, which is a recombinant BCG vaccine is essentially the live Mycobacterium tuberculosis bacteria. Of the other two “killed varieties” one is of Indian provenance – the Mycobacterium indicus pranii (MIP) – named after the man who discovered it – former director of the National Institutes of Immunology and the father of Immunology in India, Dr Gursharan Prasad Talwar. The bacteria is already being used for a leprosy vaccine which was recently piloted in Gujarat. The other has been developed by an institute based in Dartmouth. “The trials will take some time to start,” said DG ICMR Dr Soumya Swaminathan on Wednesday.

For India TB vaccine research is of crucial importance on way to its accelerated target of eliminating the disease by 2025 – ahead of the global deadline of 2035 – because it has the world’s largest number of TB patients. According to the National Strategic Plan for Tuberculosis Elimination 2017-25 that India adopted earlier this year, “TB kills an estimated 480,000 Indians every year and more than 1,400 every day.” Despite a 2012 notification making it mandatory that the government be informed of all new TB cases, there are still a million missing TB cases in India which means these people may not only be spreading the disease, worse still if they have not completed the TB medication course, they may even be spreading drug resistance forms of the disease.

ICMR is also starting a one of its kind nutrition-TB linkage study in Jharkhand where families of 2000 TB patients will be given a calorie and protein rich diet to see if that made an impact on their propensity to develop TB. India has a huge population with what is known as “latent” TB infection, individuals who are carriers of the disease but do not spread it till they become active. That “activation” it has long been believed is a function of the nutrition status of the individual.

“TB is known to be a disease of malnutrition. So the Jharkhand study is the first of its kind where we will explore whether there is indeed a link. The TB elimination plan talks of nutrition incentives for TB patients but this study will provide evidence if that is something that the government should invest in,” Dr Swaminathan added.