Mumbai’s slums test lockdown logic

Just maybe, India’s financial capital can start to look beyond its Covid-19 lockdown. An antibody testing study has found that a whopping 57% of people sampled in densely populated slum areas of Mumbai had coronavirus antibodies. Some 40% of the city’s 20 million or so residents live in similar settings, where toilets and water supply are often shared and social distancing is impossible. The result tests the logic of the city’s strict lockdown.

The study is credible, with municipal authorities partnering with the respected Tata Institute of Fundamental Research and others. The randomised sample of nearly 7,000 covers folks from three areas of the city. It’s evidence that crowding speeds transmission and that low-income groups are more vulnerable to infection. Just 16% of people sampled in more affluent parts of the same three areas of Mumbai were found to have the antibodies. 

Encouragingly, the study suggests an infection mortality rate of between 0.05% and 0.01% based on official death numbers – that’s low and would remain so, relative to many other estimates, even if the numerator is under-reported.

The findings will support politicians as they tweak policies that have reduced Mumbai to a shadow of itself. The din of rush hour traffic is no more, offices mostly sit empty, street-food vendors have disappeared and restaurants closed to diners. Public transport is curtailed, and residents are subject to a 9 p.m. curfew. Most restrictions have been in place for four months, making India’s lockdown one of the world’s strictest. 

The extreme shutdown may have initially avoided worse pressure on an under-resourced health system. But the new study suggests the measures are now impoverishing more than protecting the poor. Armies of daily-wage earners have been left dependent on food rations. With so many of them infected, Mumbai might consider loosening restrictions, enabling more people to return carefully to work.

That might, of course, increase the risk of infection for wealthier groups where lifestyle diseases are more common in Mumbai, underlining how important local factors are in managing Covid-19. And one study, however well structured, can’t provide all the answers for a given city, either. But this one does raise the possibility that if any community in the world has achieved something like herd immunity, it may be the residents of Mumbai’s slums.