Immunoglobulin-G or Ig-G antibodies start developing two weeks after the onset of infection, and last around 90 days, say doctors. While the IgG test cannot detect the presence of the virus, but a positive result indicates that the person had contracted the infection in the past, even if they were asymptomatic. Thus, several people are opting for this test to ascertain whether they have developed immunity against Covid.
Several labs pointed out that they are getting around 10 requests for antibody tests every day since the beginning of this month. Private hospitals pointed out that they are getting requests from corporate clients for these tests. As per the data, around 20% to 30% people are found to have developed antibodies.
Dr Sanjay Gupta, senior consultant & HOD, internal medicine, Medeor Hospital, Manesar, said, “This month, 15 patients have visited our hospital for the antibody tests, out of which five were found to be positive. Considering this, the positivity rate of these tests is over 25%.”
According to Anand K, CEO, SRL Diagnostics, the test helps detect specific antibodies and is accurate in indicating whether an individual has been exposed to the novel coronavirus. “The demand for these tests had slumped after an initial take-off. However, the tests have evolved and the government is using it widely in many states for sero surveillance. As per ICMR guidelines, sero surveillance testing has to be done on clusters which include industries, offices, health care workers, among others,” he said.
“Covid IgM is a useful tool to detect acute Covid infection. Positive result indicates that you have Covid infection but negative test doesn’t completely rule out Covid-19. That’s why it’s recommended that negative Covid IgM should be confirmed with the Rt-PCR, which Is the confirmatory test for Covid. Now, when it comes to Covid IgG, it signifies that the person has been exposed to Covid virus and has developed antibody against it as do the people who develop post vaccination. This exposure could be a mild sub clinical infection or a full blown Covid. Antibody doesn’t differentiate between the two. So, checking somebody’s Covid IgG isn’t a right test for acute infection.
While developing Covid IgG is good but one should not take it as a licence not to wear masks and not to practice social distancing as there have been reported cases of Covid re- infection,” said Dr. Arunesh Kumar, senior consultant & head respiratory medicine/pulmonology, Paras Hospital, Gurugram.
This test, however, would help in gauging the proportion of the population exposed to the infection, say experts. “This will help identify the cases that were asymptomatic according to rapid antigen tests,” said Dr Majeetha Nath Das, consultant, internal medicines, Columbia Asia Hospital, Gurugram.
Suraj Wadha, a resident of Nirvana Country, said, “Knowing that you have immunity provides hope which is needed at this point of time. I do not have antibodies, so I am not venturing out and I am following the norms to ensure that I am safe.”