MUMBAI: Scientists from the Haffkine Research Institute, along with the state’s medical education department (MED), are set to conduct a multi-centre clinical trial to test the use of tuberculosis vaccine BCG (Bacillus Calmette-Guerin) to treat Covid-19.While multiple trials the world over, including one by the Indian Council of Medical Research (ICMR), are looking at the vaccine’s efficacy to prevent the coronavirus disease, this trial will evaluate whether it can treat the infection. The 121-year-old institute’s trial is intended for patients who are moderately ill with Covid-19 and is likely to be carried out in small batches.It will be conducted at state-run medical colleges and has already been approved by the state and the institutional ethics committees. Confirming this, MED secretary Dr Sanjay Mukherjee said, “We are awaiting the Drug Control General of India’s (DCGI) nod to begin work. There is a lot of speculation around BCG and whether it has any impact on Covid-19. We will assess if one shot of BCG can mitigate the disease.”He said the state is aware that the idea of using BCG as a therapy could raise a few eyebrows, but there is reason to believe it could work. BCG is widely given to infants and neonates to prevent tuberculous meningitis. Sources have told TOI that “encouraging results” in a preliminary evaluation of the BCG concept has prompted the agencies to conduct a full trial. “It has been used in a handful of mild, moderate and severe cases with encouraging results,” said an official.Dr Mukherjee confirmed that the initial experience on a handful of patients has been encouraging, but only a full trial would say whether patients will benefit from it. Some city doctors, however, expressed scepticism and said that an immune-modulator like the BCG vaccine takes at least two to four weeks to stimulate immunity.“If it’s a therapeutic trial, how will they measure whether it worked or not as the disease’s natural course is two weeks? In most cases, either patients are going home by two weeks or succumbing to the infection. The bottomline is if the patient is too ill, how will they monitor?” said a senior infection consultant, adding that an Australian and a Dutch study are investigating the effect of BCG vaccination in healthcare workers to see if it offers any natural immunity against Covid-19.