Even as the previous sero survey suggested declining antibodies in the slum population, the densely populated areas in the city have mostly remained untouched in the third wave. While it may be attributed to less testing, slums are contributing around 20 per cent of daily Covid-19 cases as compared to high-rises.

During the first wave, after the initial cases reported in towers in April-May 2020, slums remained at the centre with maximum cases and fatalities. The Brihanmumbai Municipal Corporation faced challenges to curb the infection in these densely populated areas. The second wave, though, hit high-rises harder. Sero surveys conducted after the second wave suggested that the third wave may hit the slums again. But, three weeks into the wave, cases from slums account for 10 to 15 per cent of the total cases.