New Delhi, Apr 10 (PTI) The two new tuberculosis vaccines could be safe for use in adults and children in India but may not provide protection against all forms of the infectious bacterial disease, according
to phase-3 trial results published in The British Medical Journal.
Phase-3, a randomised clinical trial, is a final-stage study that compares a new treatment against a current procedure to determine safety and efficacy.
Researchers, including those from the Indian Council of Medical Research (ICMR) in Delhi, conducted the PreVenTB trial to assess the safety and efficacy of the two new vaccines -- VPM1002 and Immuvac -- in lowering incidence of tuberculosis (TB).
In India, the Bacillus Calmette-Guérin (BCG) vaccine is administered to infants at birth to prevent TB. VPM1002 is a recombinant BCG vaccine developed by Serum Life Science Europe GmbH, a Germany-based pharmaceutical company.
A recombinant vaccine makes use of genetic engineering to produce antigens from a pathogen to trigger an immune response.
Immuvac is developed by the ICMR and Ahmedabad-based Cadila Pharmaceuticals and is an inactivated vaccine made using a non-infectious version of the pathogen.
The researchers said while the BCG vaccine is effective against severe forms of TB in young children, it does not offer protection for adolescents and adults.
Over 12,700 household contacts -- aged six and above -- of TB patients from 18 sites across six states and Union territories, including Delhi, Maharashtra and Tamil Nadu, between July 2019 and December 2020 were analysed.
The participants were randomly assigned to receive a dose of either VPM1002, Immuvac, or a placebo (4,239 in each group) and were followed up for 38 months.
A second dose was administered to 11,829 participants one month later. A total of 12,295 participants (96.7 per cent of those enrolled) completed 38 months of follow-up.
Both vaccines were found to be safe and induced an immune response. "Both vaccines were safe but did not show any efficacy against all forms of microbiologically confirmed TB or pulmonary TB," the authors wrote.
The trials also found that while neither vaccine offered general protection against TB or prevented latent TB infection, both demonstrated an ability to prevent the progression to active TB in those who developed latent TB.
However, VPM1002 showed an effectiveness (50.4 per cent) against extrapulmonary TB across all age groups, including those aged 36-60 years -- the result suggests a potentially significant public health benefit, as extrapulmonary TB which affects organs beyond the lungs is often associated with a higher risk of mortality than pulmonary TB, the researchers said.
Among children, the VPM1002 provided protection against all TB, pulmonary and extrapulmonary, in the six to under-14 age group, while Immuvac provided protection against extrapulmonary TB only in the six to under-10 age group.
However, neither vaccine protected children and adults who were underweight, suggesting that nutritional support may be needed along with vaccination, especially for younger children, the authors said. PTI KRS ARB
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