Chandigarh, Dec 6 : A day after Haryana Health Minister Anil Vij tested positive for coronavirus, he said on Sunday that the doctors had informed him that a second dose of Covaxin vaccine would be administered to him 28 days after the first one and he would develop antibodies 14 days after the second one. In a series of tweets on Sunday, he said despite taking precautions, he got infected with coronavirus. "I am undergoing treatment in Civil Hospital in Ambala and feeling better now," Vij said. On November 20, he was given a shot of Bharat Biotech's Covaxin for which he had volunteered. Besides Vij, over 400 people from Haryana, including the Vice Chancellor of Pandit Bhagwat Dayal Sharma Post Graduate Institute of Medical Sciences (PGIMS), Rohtak, O.P. Kalra, participated in the trials about India's first indigenous vaccine for the highly infectious coronavirus. PGIMS Head of the Department of Pulmonary and Critical Care Unit, Dhruv Chaudhary, said it was not known whether Vij received a vaccine or placebo, as shots for the volunteers were selected randomly by a computer. On its part, Hyderabad-based Bharat Biotech said the efficacy of its Covid-19 vaccine could be determined only 14 days after a second dose. "Covaxin has been designed to be efficacious. Covaxin clinical trials are based on a two-dose schedule, given 28 days apart. The vaccine efficacy will be determined 14 days post the second dose," said the company in a statement. /IANS