HYDERABAD : A single dose of Covid-19 vaccine is sufficient for an infected person as there was a greater antibody response when compared with those who have had no prior infection, according to a study released by AIG Hospitals on Monday.The city-based AIG Hospitals recently published a study conducted on 260 healthcare workers, who got vaccinated between January 16 and February 5, in the International Journal of Infectious Diseases (a peer-reviewed journal).The study was designed to assess the immunological memory response in all those patients.All patients were given the Covishield vaccine.The study also said Memory T-cell responses elicited by a single dose of vaccine were significantly higher in the previously infected group compared.