State to conduct serological survey at selected zones

Kolkata: State Health department has identified areas in the city and its adjoining districts of North 24-Parganas, South 24-Parganas and Howrah where it would conduct a serological survey in a large scale in collaboration with various civic bodies.

The main purpose of the move is to find out the prevalence of IgG antibodies among the people in the infected areas. Blood samples would be collected from the people on a random basis and it would be traced if they had developed any sort of antibody in their bodies.

The IgG test may not be useful for the detection of acute infections but it shows if a particular infection occurred among a section of people in an area or if they have developed antibodies in the blood components.

A serological survey includes IgG Enzyme-Linked Immunosorbent Assay (ELISA) test, which looks for proteins found in COVID-19 antibodies.

The State government is trying to examine if an immunity system has been developed among the people in the containment zones.

"When a person is asymptomatic even after being infected with the virus and develops antibodies, he/she does not necessarily require a hospitalization.

These persons however can infect at most three persons who come in close contact," a health expert said.

In the past few weeks the rate of infection has gone up manifold not only in the city but also in North 24-Parganas, Howrah and South 24-Parganas.

A proposal has also been sent by the health department to the Indian Council of Medical Research (ICMR) expressing its interest to conduct a serological survey in the mostly infected parts.

More than 10 spots have been identified for the survey in all the districts including Kolkata, sources in the Health department

said.

Earlier the ICMR in association with the health department had carried out a serological survey and found the prevalence of IgG antibody in

57 people in the city out of 396 whose blood samples were tested.

Around 14.39 per cent of the total number of people undergoing Serosurvey had tested positive with Covid infection in the city.

They had contracted the virus but also developed antibodies within their body.

They were all asymptomatic and did not require hospitalization. On the previous occasion, the survey was also conducted in five more districts as well such as Alipurduar, Bankura, Jhargram, South 24-Parganas and East Midnapore. As many as 400 samples were tested from each district out of which round 10 persons were found positive in South 24-Parganas, 4 in Alipurduar, 3 in East Midnapore and one each in Bankura and Jhargram.