More than half of the residents in the densely populated slums of India’s financial capital of Mumbai had been exposed to the coronavirus and developed antibodies as of early July, a city-commissioned study has found, sparking a debate over whether more testing is needed in the metropolis. Blood tests on nearly 7,000 randomly selected samples from three wards of the city with a population of a little over 1.5 million indicated that 57% of people in those areas had been exposed to the virus and developed antibodies….