According to a study published in the New England Journal of Medicine, the BCG vaccine did not reduce the risk of developing COVID. In the study, the researchers from the Murdoch Childrens Research Institute in Australia enrolled 3,988 healthcare workers from Australia, the Netherlands, the UK, Spain, and Brazil.

A study published in the journal Science Advances in 2021 by researchers from the ICMR-National Institute for Research in Tuberculosis and the ICMR-National Institute of Epidemiology suggested that BCG could potentially act to inhibit biomarkers of inflammation by immune cells in the blood, potentially lowering the risk of COVID infections in older adults.

Last year, a Murdoch Childrens Hospital-led study published in Clinical and Translational Immunology found that the BCG vaccination elicited an immunological response associated with protection against severe COVID-19. Furthermore, according to the most recent research, the probability of symptomatic COVID-19 was 14.7% in the BCG group and 12.3% in the placebo group throughout the first six months of the experiment.

The lead author of the study, Professor Nigel Curtis, stated that symptomatic COVID-19 was frequently observed in the BCG group, which might indicate the stronger immune responses induced by the vaccine. He noted that when they analyzed the immune cells of the participants, they observed that the BCG vaccine altered the immune response to COVID-19.

Hence, he concluded that a stronger response induced by BCG can be beneficial in killing the virus more rapidly and protecting against progression to more severe disease. 

(Source: https://www.thehansindia.com/life-style/health/100-year-old-bcg-vaccine-does-not-protect-against-covid-19-study-794901 )