15-30% People in Many Containment Zones May Have Contracted & Recovered from Covid-19, Reveals ICMR Serosurvey

The findings of the first population-based serosurvey, conducted by the Indian Council of Medical Research (ICMR) to evaluate the extent of exposure to Covid-19, show that nearly 30% of the population in several containment areas may have acquired the disease and recovered.

According to a report in The New Indian Express, ICMR, with the assistance of state governments, National Centre for Disease Control and India's office of World Health Organisation procured close to 24,000 samples from 70 districts across India, from randomly chosen individuals.

The survey conducted by the ICMR revealed that in many containment areas, 15 to 30 per cent of the population has been exposed to the infection, the report added quoting government sources as saying.

Sources privy to the serosurvey report told News18 that in Mumbai, Pune, Delhi, Ahmedabad and Indore, the infection rate is much higher than other containment areas.

The findings do not imply the presence of herd immunity but it shows that immunity to the infection is developing gradually in India. It also means that people residing in these areas will be the first to develop herd immunity, which will take time.

The findings further reveal that there are scores of asymptomatic patients in India and infection is much more widespread than what is being reflected.

A sero-survey involves testing of blood serum of a group of persons to check for the presence of antibodies against that infection to know who has been infected in the past and has recovered.

Depending on the level of sero-prevalence of infection, appropriate public health interventions can be planned and implemented for prevention and control of the disease, the Indian Council of Medical Research (ICMR) had said earlier.

The antibody tests for the ICMR serosurvey have been carried out using the COVID Kavach Elisa testing kit which was developed by the National Institute of Virology under the ICMR. The test kit has been validated at two sites and has high sensitivity and specificity, thus making it a better tool for surveillance of infection spread in a community compared to the rapid antibody test kits.

It is an IgG Elisa-based test. This means that the test will be done to detect the Immunoglobulin G (IgG) antibody.