Addressing a press conference in Delhi, AIIMS director Prof Randeep Guleria said that phase 1 of Covid-19 vaccine trial will be done on 18-55 year age group. “Phase 1 trial has to be done on people who have no co-morbidity. Underline problems also need to be checked by conducting blood tests,” he said. A total of 1,125 samples have been collected, out of which, 375 will be studied in the first phase.