A study among healthcare workers in Assam has found that a single dose of Covishield is sufficient for previously infected persons. The study was conducted jointly by three premier institutions - the ICMR, Regional Medical Research Laboratory and Assam Medical college located at Dibrugarh. Speaking exclusively to NDTV, Dr Gayatri Gogoi, of Assam Medical college, said how findings may help in the satisfaction of vaccine beneficiaries and also save vaccines.