One-third of Indian Population in hotspots exposed to COVID-19 and silently recovered, reveals ICMR’s serosurvey

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Preliminary findings from the Indian Council of Medical Research (ICMR)’s population-based serosurvey has revealed that about one-third of India’s population inside various containment zones and hotspots may have already been infected with the novel coronavirus and may have recovered.

The report is yet to be published and it states that between 15-30 per cent of the population has been exposed to the infection within containment zones and hotspots. These findings have been presently shared with the Union cabinet secretary and the PMO.

The report also points to the fact that the infection rate is higher in cities such as Mumbai, Pune, Delhi, Ahmedabad and Indore, where the infection rate is about 100 times more than other high-burden hotspots, said sources.

The research body had conducted this crucial survey to assess the extent of exposure to SARS-CoV-2 in high-risk zones. According to the testing protocol, samples were collected from 10 high-burden hotspot cities – these included 10 hotspot cities Mumbai, Thane, Pune, Ahmadabad, Surat, Delhi, Kolkata, Indore, Jaipur and Chennai.

500 samples each were collected from 10 randomly chosen containment areas in each of these cities. In addition, 400 samples each from other 60 districts across 21 states — categorised on the basis of low, medium and high caseload — were also collected. The ICMR had earlier stated that these cities contribute to nearly 70 per cent of India’s total number of cases of Covid-19.

ELISA-based antibody tests have been used to conduct the survey for which blood samples of people are collected to look for the presence of antibodies of coronavirus. Earlier, these same tests were supposed to be conducted using the rapid antibody test kits imported from China. The Chinese antibody test kits turned out to be faulty and were widely discredited, which put a dent in the serosurvey.