The Greater Chennai Corporation (GCC), on Thursday, conducted antibody tests on 564 staff members to check for COVID-19 exposure. Of the 564 employees tested, 112 were found to have developed antibodies against the coronavirus.
According to a statement from the GCC, antibody testing for its staff members is the first step towards conducting the test on a larger population to find out the levels of exposure to the SARS-CoV-2 virus that causes COVID-19. Of the 564 employees tested on Thursday, 452 employees were found to have had no exposure to the virus. However, 84 employees tested had developed IgG antibodies.
The blood samples of 28 other staff members revealed IgM antibodies. These 28 employees were then made to undergo Real Time Polymerase Chain Reaction (RT-PCR) test, considered the gold standard to detect the SARS-CoV-2 virus and have been isolated.
Rapid antibody tests help authorities to determine whether a person has been exposed to the novel coronavirus by checking if their blood has the antibodies against this particular virus. Antibodies are made by the body’s immune system in the blood to fight against bacterial, viral and allergic infections. According to a report in The Wire Science, the Rapid Antibody test kits provided by the Indian Council of Medical Research (ICMR) tests the blood for an antibody called Immunoglobulins (IgG, IgM and IgA).
IgM is the first antibody produced in the blood when the body detects a new infection. IgG type of antibody is developed in the blood after an infection. Essentially, in rapid tests, if the blood samples show the presence of IgM, it indicates that the person has been recently exposed to the virus and hence he or she will be made to undergo an RT-PCR test to check for COVID-19. If the sample drawn from a person shows the presence of IgG, it indicates that the person was formerly exposed and is now immune to the infection. If both these antibodies are absent, it would mean that the person has not been infected so far.