A letter sent by Dr Balram Bhargava, the Director General of ICMR pushing for a 15 August release for indigenous Covid vaccine, Covaxin triggered questions about its safety and efficacy. Can clearance processes be cut short and how does Covaxin developed by Bharat Biotech & NIV work? In episode 514 of ThePrint's #CutTheClutter, Shekhar Gupta lifts the layers, and lists the 4 vaccines cleared for human trials in India