NEW DELHI : A sero-prevalance survey conducted in the first week of August in Delhi has found that 79 of the 257 people who recovered from COVID-19 did not have antibodies against the virus.About 15,000 representative samples were taken in the August 1-7 survey from 11 districts and tested for antibodies (IgG) against the virus.Blood samples of 257 people who had tested COVID-19 positive earlier and then recovered, were also taken during the survey to test if they had antibodies.Seventy-nine of these people did not have the antibodies against the virus, according to its report of the August serological survey.The exercise was undertaken for a comprehensive assessment of the COVID-19 situation in Delhi and to formulate strategies based on.