Why BCG vaccine is ineffective: Grandma’s medicinal concoction to deworm the digestive system on regular basis is not without a solid scientific backing. A team of Indian researchers has now found out that the presence of worms in the stomach makes the vaccination against the killer tuberculosis relatively ineffective

By Syed Akbar
Hyderabad:  Grandma’s medicinal concoction to deworm the
digestive system on regular basis is not without a solid scientific
backing. A team of Indian researchers has now found out that the
presence of worms in the stomach makes the vaccination against the
killer tuberculosis relatively ineffective.

Almost every child born in the country receives BCG (Bacillus
Calmette-Guerin) vaccine dose within a few days of birth. The BCG
vaccine has however been found to be ineffective in certain cases and
some people, though vaccinated, develop tuberculosis. BCG is covered
under universal immunization programme in India, and children get the
initial and booster doses free of cost. Yet, TB has emerged as a major
health nuisance in India and even in developed nations like the United
Kingdom.

Scientists from the Institute of Microbial Technology, Chandigarh,
point out that infections with parasitic worms interfere with the BCG
vaccination and render it less effective. The finding was published in
the latest issue scientific journal, Trends in Molecular Medicine.

IMT senior scientist Dr Javed Agrewala explains that BCG does not work
well in TB endemic regions because exposure to prevalent mycobacterial
strains triggers the production of antibodies that counteract the
vaccine. “In addition, infections with parasitic worms called
helminths interfere with protective immune responses induced by
BCG”.

India has a large number of TB cases despite vaccination. It also has
several thousands of latent TB cases where the TB bacteria continue to
live in the body but without causing any disease. The United Kingdom
has made TB tests mandatory for Indians visiting the country for
periods exceeding six months. On one hand, the BCG vaccine has lost
its efficacy and on the other disease has become resistant to a number
of known drugs, further complicating the problems of health planners
and doctors.

According to a Cell Press release, there is an immediate need to
develop new type of vaccine to prevent the spread of tuberculosis as
the existing vaccine BCG has lost its sheen to an extent. Dr Agrewala
proposes novel synthetic vaccines based on
lapidated-promiscuous-peptide to protect people in TB endemic
countries like India.

The synthetic vaccines are safer than BCG because they do not contain
infectious material, the release said adding that they generate
long-lasting, protective immune responses and are not influenced by
pre-existing antibodies.