India's coronavirus count is now over 1.5 million but cities that were hit the hardest in the past few months have seen cases slowing. SERO-surveys conducted in Delhi, Ahmedabad and Mumbai are helping policymakers understand the scale of the spread of the virus as well as the prevalence of antibodies in the larger population.
The SERO-survey in Mumbai which was released yesterday showed that over 40 percent of the population could have antibodies to COVID-19. This is much higher than the 23.5 percent in Delhi and 17.6 percent in Ahmedabad. Many scientists and studies have claimed that a 60-70 percent prevalence of antibodies in the general population could mean the so-called herd immunity.
But, there are a few caveats - nearly 7,000 people who were surveyed in Mumbai belong to 3 areas of Dahisar, Chembur, and Matunga. So extrapolating this for the entire city may not be accurate. Which is why the local authorities are planning more surveys in different areas.
Nonetheless, this survey does provide some crucial insights. In Mumbai's slums, the prevalence of antibodies in the population is as high as 57 percent. This is largely due to the dense population and lack of sanitation. In housing societies, the prevalence of antibodies is at a lowly 16 percent. This means a large section of the population who live in gated communities and societies remain vulnerable.
But here is the big finding - as thing stand, the case fatality rate in Mumbai is 5.5 percent. The city has over 1 lakh confirmed cases. But, according to this survey, 50-70 lakh people may have been exposed to the virus and this leads to a massive drop in the mortality rate to just under 0.05 to 0.1 percent.
Doctor VK Paul, a member of the NITI Aayog and also a member of the Task Force on the coronavirus against COVID-19 discussed the fine print.