NEW DELHI : Covaxin is a two-dose anti-coronavirus vaccine and Haryana Health minister Anil Vij, who had volunteered for its phase-three trial, was given only the first dose, the Union Health Ministry clarified on Saturday hours after the minister announced that he has tested positive for COVID-19.Vij had offered to be the first volunteer in the phase three trials for Covaxin, an indigenous potential vaccine against COVID-19 being developed by Bharat Biotech in collaboration with the Indian Council of Medical Research (ICMR).On Saturday, the Union health ministry said, "The antibodies against the infection build up in a human being only after a specific number of days pass after the second dose of the vaccine is taken.