AHMEDABAD : Around 40 per cent of COVID-19 patients lost antibodies post their recovery from the disease, revealed a survey by the Ahmedabad civic body covering 1,800 previously infected people in the city.The loss of antibodies makes people who have recovered from the disease susceptible to reinfection, said Dr Bhavin Solanki, medical officer of the Ahmedabad Municipal Corporation (AMC), on Friday.The survey was conducted on 1,800 persons, who tested positive for coronavirus between March and July through antigen tests, said Dr Jay Sheth, associate professor of civic-run MET Medical College.Developing antibodies means a person contracted COVID-19, recovered and subsequently developed them against the viral disease."The survey has revealed.