The Indian Council of Medical Research in collaboration with other key stakeholders is conducting a population-based sero survey to estimate the prevalence of coronavirus infection among the Indian population.
According to an expert associated with the survey, the exercise can help to ascertain if there has been community transmission of the respiratory disease in these areas.
The survey would be conducted in 69 districts of 21 states and Union Territories, the apex health research body said in a statement on Tuesday.
Maharashtra, Rajasthan, Uttar Pradesh, Gujarat, Madhya Pradesh, Chhattisgarh, West Bengal, Assam and Bihar are some of the states where the survey would be conducted.
The household-level cross-sectional survey will cover 24,000 adults distributed equally across four strata of districts categorized on the basis of COVID-19 cases, the ICMR said in a statement.
The move was announced as the death toll due to COVID-19 rose to 2,293 and the total number of cases climbed to 70,756 in the country on Tuesday, according to the Union health ministry data.
As part of the study, people from Red, Orange and Green zones in a district will be tested for COVID-19 at random to check if they have developed antibodies against the infection even though they are asymptomatic or show mild symptoms, the expert said.
"The ICMR, New Delhi, in collaboration with the Department of Health and Family Welfare, Government of India and National Centre for Disease Control with support from state health departments and key stakeholders, including WHO, India is conducting a community-based serosurvey to estimate the prevalence of SARS-CoV-2 infection in the Indian population," the statement said.
The survey is coordinated by ICMR's National Institute of Epidemiology (NIE) and National Institute of Research in Tuberculosis (NIRT), Chennai.
The survey will involve collection of venous blood samples from 400 randomly selected individuals (one per household) from 10 clusters in each district.
"Sera from these individuals will be tested for the presence of IgG antibodies using ELISA test developed by ICMR-National Institute of Virology (NIV), Pune. The results of the survey will provide information about the spread of SARS-CoV-2 infection (COVID-19) in different parts of the country," the ICMR said.
The officials said the study would have started earlier as it was planned to be conducted with the rapid antibody test kits brought from China. But after these test kits showed inaccurate results in some places, the study had to be postponed.
The health ministry said the survey would be conducted in six districts of Maharashtra, including Beed, Jalgaon, Ahmednagar, Sangli; three districts of Rajasthan like Dausa, Jalore; nine districts of Uttar Pradesh like Bareilly, Unnao, Saharanpur, Mau; three districts of Gujarat like Mahisagar, Narmada; three districts of Madhya Pradesh like Ujjain, Gwalior.
Besides the health ministry is also initiating hospital-based surveillance to monitor the trend of infection in all districts.
The survey will be conducted at 10 health facilities (six public and four private) and would test outpatient attendees and pregnant women among the low-risk group, and health care workers among the high-risk population.
At least 100 samples of healthcare workers from selected districts per week and 400 per month would be tested.
Besides, 50 samples each of the outpatient attendees and pregnant women per week and 200 samples per month would be collected, the document stated.
Throat and nasal swabs will be collected for RT-PCR tests and samples should be tested in a one-time pool of 25, it said.