Private laboratories have kick-started antibody testing for anyone who wants to undergo the same, with most requests coming from the private sector — people attached to salons, film industry, private hospitals, and industrial and corporate offices.
Thyrocare, which has conducted about 5,000 ELISA (enzyme-linked immunosorbent assay) antibody tests across India, said it has found 8 per cent of those examined testing positive for antibodies against the coronavirus.
Several of the samples it took in Mumbai were part of a sero-surveillance being undertaken by BMC along with Niti Aayog.
The ELISA IgG antibody test involves taking a blood sample of a person to check whether he or she has developed antibodies against an infection. Antibodies take two weeks to develop after exposure to infection. A person may or not develop symptoms but will still develop antibodies to fight the infection.
This test, used as surveillance tool, indicates how many may have got exposed a virus.
In European countries, the test is being used as an “immunity passport” for people wanting to return to work while being assured that they have immunity against Covid-19.
“We have mostly received requests from corporate offices in different parts of India that wanted its employees to resume work. We found that 10 per cent of those examined in cities and 5 per cent in smaller towns tested positive. On an average, 8 per cent people tested had been exposed to Covid-19 and developed antibodies,” said Dr A Velumani, founder of Thyrocare.
Thyrocare is charging Rs 600 per test and results are generated in 24 hours. The lab’s head of operations, Dr Caesar Sengupta, said they started antibody testing from June 26, and have been testing a mix of high-risk population and the general population. “We are also testing industrial labourers who are returning to work,” he added.
Suburban Diagnostics started antibody testing from Monday, and has tested 250 samples so far. The lab is charging Rs 950 for walk-ins, and Rs 1,450 for home testing.
“We are receiving queries from health workers who want to know if they have been exposed to the virus. Salons want their employees to be tested. Since the film industry has started shooting, several are coming for ELISA tests,” said Dr Sanjay Arora, founder and managing director of Suburban Diagnostics.
The lab found 25 per cent of those examined tested positive for antibodies but Arora said more tests are needed to draw a definitive conclusion on the exposure rate. “Testing 250 samples is a small number. This may or may not indicate actual exposure to the virus among the general population,” Arora said.
Dr Nilesh Shah, group president at Metropolis, said they started ELISA testing in 45 labs on Tuesday and have tested around 500 people so far. “We have mostly tested corporate employees till now. Some housing societies are also approaching us,” he said, adding that they are yet to analyse the positivity rate and will a require larger pool to do do.
Until last month, Indian Council of Medical Research (ICMR) guidelines had allowed antibody testing for frontline and health workers, in containment zones, and for government approved sero-surveys.
On June 23, in its revised guidelines, while ICMR maintained RT-PCR (real-time polymerase chain reaction) test was the “gold standard” for detecting Covid-19 infection, it allowed private labs to perform ELISA antibody tests for a broader spectrum.
A spokesperson for SRL Diagnostics said they are still evaluating protocol and will soon start performing the tests.
India so far has 1,000 approved Covid-19 testing labs, 730 of them in the public sector. In May, ICMR had conducted a sero-surveillance of 26,400 people and found 0.73 per cent positive for antibodies, indicating the exposure of virus was lower than 1 per cent.
India so far has 1,049 approved labs. Among them, 761 are in the public sector.
📣 The Indian Express is now on Telegram. Click here to join our channel (@indianexpress) and stay updated with the latest headlines