A sero-surveillance study done in Mumbai has revealed that 57 per cent of slum population and 16 per cent of non-slum residents in three civic wards have already developed antibodies.
The tally suggests more people have already been affected by Covid-19 compared to the official tally. The survey began on June 3 collecting an estimated 8,870 samples from slum and non-slum populations across three civic wards. The BMC is going to conduct another survey that will provide information about infection spread and throw light on herd immunity as well, it said.
A serological survey involves testing of blood serum of individuals to check for the prevalence of antibodies against infection. The civic authorities claimed the result indicates that "asymptomatic infections are likely to be a high proportion of all infections".