WHO emphasizes the importance of randomised controlled trials of the vaccine to understand its safety and efficacy before using it on healthcare workers.
Randomised controlled trials using BCG vaccine are under way in the Netherlands and Australia to find out whether the vaccine can reduce the incidence and severity of Covid-19.
According to an earlier study, there is an association between countries that have a universal BCG vaccination and reduced coronavirus cases.
It argues that countries that have deployed the BCG vaccine in their immunisation programmes have seen fewer deaths from Covid-19.
The BCG vaccine enhances the innate immune response to subsequent infections which might reduce viral load after Covid-19 exposure, with a consequent less severe Covid-19 and more rapid recovery.
Views in India:
According to the Translational Health Science and Technology Institute (THSTI), Faridabad, the vaccine can prevent intracellular infections, so its protective effects against Covid-19 is a biologically plausible hypothesis.
It will be premature for India, that has had a consistent TB vaccination policy since 1968, to take comfort from the study.
Five reasons countries should wait for the results of the BCG vaccine randomised controlled trials:
The association of fewer Covid-19 cases in countries that have a universal BCG vaccination programme is based on population rather than individual data.
The benefits of the BCG vaccine given at birth are unlikely to reduce the severity of Covid-19 decades later.
The beneficial effects of the BCG vaccine might be altered by subsequent administration of a different vaccine and become less effective after longer periods.
There is a remote possibility that the BCG vaccine ramps up the immune system leading to worsening of Covid-19 in a small population of patients with a severe disease.