Over 90% of people in Delhi have antibodies against COVID-19, stated sources after the sixth sero survey report of the city was prepared. 

Every district has recorded around 85% seropositivity. Sources revealed that more women, compared to men, have developed COVID antibodies. The figure includes antibodies developed through vaccination. Till Sunday, around 86% of the Delhi population had received the first dose of a COVID-19 vaccine and around 48% have received both doses.

Scientists are still not sure as to what percentage of antibody carrying population is required for herd immunity. An Infectious Diseases Society of America briefing in August had stated that the Delta variant had taken the threshold for herd immunity to more than 80%, and potentially reaching 90%... (NDTV, October 27, 2021)