Serum Institute may give India its first adult tuberculosis vaccine

Will be critical to the success of India's drive to eliminate TB by 2025

Soon, India’s fight against tuberculosis (TB) is likely to have another weapon in its arsenal – an adult TB vaccine.

According to government sources, a recombinant Bacille Calmette–Guérin (rBCG) vaccine may soon be available for adults in India, thanks to Pune-based Serum Institute of India’s (SII’s) tireless efforts.

“SII is working on the rBCG vaccine. The Phase 3 clinical trials on adults are on. The data may be unblended soon,” said a senior government official in the know. He added that the rBCG vaccine for adults may be available within a year or so.

SII did not comment on the matter.

This can be critical to the success of India’s TB elimination drive by 2025.

Raghuram Rao, additional deputy director general, central TB division, Ministry of Health and Family Welfare, said, “Around 30 per cent of the population already has the TB bacteria in their bodies. The bacteria start to multiply in immunocompromised individuals. If nutrition balance is maintained, there is only a 10 per cent chance in one’s lifetime to contract the TB disease.”

At present, the BCG vaccine is administered to infants below a year old. Rao says it protects children from severe forms of TB in childhood. Adults, however, do not have any vaccine cover as yet.

The UK’s National Health Service website notes: “The BCG vaccination is rarely given to anyone over the age of 16 because there is little evidence it works very well in adults. But it’s given to adults aged 16 to 35 who are at risk of TB through their work, such as some health care workers, veterinary staff, and abattoir workers.”

The rBCG vaccines are manufactured through advanced technology that allows the insertion of foreign genes, or over-expression of native genes, into the BCG vaccine.

SII has already sought approval from India’s drug regulator to allow the rBCG vaccine (VPM1002) for children up to the age of six years for prevention of TB, based on data from the South African trials.

SII had presented data from the South African trials on infants before the subject expert committee (SEC) advising the Central Drugs Standard Control Organization in April. A Phase 2/3 trial with the objective of prevention of TB in 2,000 adult participants is ongoing.

The SEC had then said that SII should submit safety and immunogenicity data in the proposed indication and age group of children up to six years for consideration of its proposal, the minutes of the meeting showed.

If India decides to expand the rBCG cover to children up to six years of age, then that too would significantly increase the coverage. Moreover, as data from the ongoing adult trial (over 2,000 participants) is expected, the same rBCG vaccine cover can be expanded further to adults.

Moreover, a Phase 3 clinical trial of the rBCG vaccine being conducted by the Indian Council of Medical Research (ICMR) in 12,000 participants of age on or below six years healthy household contacts in the country is ongoing. ICMR is yet to submit the clinical trial data.

Government sources said the data from the trials is likely to be unblended soon.

Jacob John, senior virologist and former head of the departments of clinical virology and microbiology at Christian Medical College, Vellore, told Business Standard that typically a TB infection does not prevent one from getting TB again.

“Therefore, one has to see how effective a vaccine can be in protecting against such a disease. However, if a vaccine is innovatively designed, such that it offers greater protection than a natural infection, it may work,” said John, adding that any adult vaccine against TB is a welcome step.

India reported a sharp 19 per cent rise in TB cases in 2021 over the previous year, revealed the India TB Report 2022. At the same time, there has been an increase in the mortality rate due to all forms of TB between 2019 and 2020 by 11 per cent in India. 

Taking vax cover

1. SII has sought approval for recombinant BCG (rBCG) vaccine for children up to six years
2. BCG vaccine now given to infants below a year old
3. Trials on 2,000 adult participants on for rBCG vaccine
4. 30% adults estimated to carry TB bacteria in their bodies
5. Lowering of immunity leads to bacteria multiplying and getting the disease