The Oxford University's Covishield vaccine for coronavirus has drawn an immune response even in the elderly, who are among the groups vulnerable to the disease, Adar Poonawala, the chief of Serum Institute of Imdia, which is partnering the UK-based premier university, told NDTV today. The vaccine, he said, is "very safe". "Thousands of people have had it in India and abroad so we are cracking on track with no safety concerns," he added.