The Indian Council for Medical Research (ICMR) will be initiating a study in 75 of the worst affected districts for community transmission of the coronavirus.
"As a part of the study, people from red, orange and green zones in a district will be tested for COVID-19 at random to check whether they have developed antibodies against the infection even though they remained asymptomatic or showed mild symptoms.”
"The presence of antibodies in them will establish that they were infected by the virus and were able to fight it off. They did not know they had contracted the disease as they had no symptoms," an official explained.
The exercise will also help ascertain if there has been community spread of the disease, the official said. Community spread is a stage where the source of the infection cannot be traced. Districts with high population and heavy inter-state movement of people will be selected for the study to represent the respective state, the sources told PTI.
"The quantum of sampling for the study is yet to be decided. The study will only make sense if it has a decent sample size," another official said.
An ICMR official told the Hindu that the study was supposed to be conducted in the first week of April. “We had drawn up places based on hotspots, which being dynamic have changed; a final list will be announced soon,” he told the newspaper.
The study was reportedly supposed to be conducted earlier through rapid antibody tests but was then postponed due to varied results.
The modality of testing is yet to be decided, but either an ELISA (enzyme-linked immunosorbent assay) antibody test which is a kind of blood test or pool sampling with RT-PCR test could reportedly be used for the study.
The ELISA test kits are awaiting ICMR's validation, which is expected soon. The ELISA test is similar to rapid antibody tests as it looks for antibodies in the blood to ascertain if one has been infected with the coronavirus or not.
At present, efforts are being made by the government to identify asymptomatic people through contact tracing and community surveillance.
The Union Health Ministry recently classified 130 districts in the red zone, 284 in the orange zone and 319 in the green zone across states, taking into consideration COVID-19 cases, doubling rate, the extent of testing and surveillance feedback.
In addition, the Health Ministry on Saturday said it would deploy central teams in 10 states that have witnessed or are witnessing high COVID-19 cases to assist their health departments to facilitate the management of the outbreak.
These are besides the 20 central teams of public health experts sent earlier to 20 high case-load districts on May 3, the health ministry said in a statement on Saturday, adding a high-level team was recently deputed in Mumbai to support Maharashtra's efforts in COVID-19 response and management.
According to the health ministry statement, the central teams comprise a senior official from the health ministry, a joint secretary-level nodal officer and a public health expert.
The teams are being sent to Gujarat, Tamil Nadu, Uttar Pradesh, Delhi, Rajasthan, Madhya Pradesh, Punjab, West Bengal, Andhra Pradesh and Telangana, it said.
With PTI inputs