As part of efforts to step up testing for coronavirus, the Indian Council of Medical Research has invited manufacturers to supply 5 lakh antibody kits for diagnosis of infection. Experts in the government point out that the serological test will act as a screening process, as was done in South Korea, one of the few countries which has been able to flatten the pandemic curve.
Dr V Ravi, Head and Senior Professor, Department of Neurovirology, NIMHANS, who specialises in public health virology and development of indigenous kits, told The Indian Express that considering the large number of suspected patients being quarantined in the country through contact tracing of just a single patient, the antibody testing for COVID-19 will act as a “screening test” that will give quick results in a few hours.
“The conventional RT-PCR test (reverse transcription polymerase chain reaction) being done in India detects the virus genetic material, which is the RNA. The antibody test will detect the body’s response to the virus. The former is direct evidence and the latter the indirect evidence. Therefore, the antibody test will be used as a screening test where large number of people are being quarantined and where everybody cannot undergo RNA test.”
“Since there is shortage of PCR kits, the test is complicated, expensive and time-consuming. What South Korea did was that they started screening people with history of travel and contact, and conducted the serological test using the antibody kit. The antibody will give an indication that a person has been exposed to the virus. If the test is positive, then you can collect the swab and do an RNA test using the PCR kit. This will be a two-stage process,” Dr Ravi said.
“The advantage is that the antibody test is very simple. Just a drop of blood is required and the results will be available in just one-two hours. Some kits require whole blood and some kits require blood to be centrifuged. However, one needs to remember that is not a test that will definitely tell you that a person is infected with COVID-19 infection. It is only for screening,” he said.
Inviting suppliers to submit quotations for a “tentative requirement” of 5 lakh antibody kit, ICMR said that supply has to be “ensured” to six locations in the country: Dibrugarh, Mumbai, Chennai, Hyderabad, Bhopal, and Delhi. Currently, India is only conducting the RT-PCR test; the government has fixed a Rs 4,500-cap for a RT-PCR test in a private laboratory. The ICMR has also asked suppliers for a quotation on procurement of 7 lakh RNA extraction kits.
Dr Ravi flagged that the serological test will only help screen more number of suspected patients in a shorter duration, but is not aimed to be a tool for mass testing. “Remember, it will be a test to screen persons who have come in contact with COVID-19 patients. If Mr X is COVID positive, and by contact tracing, it is revealed that 1,000 persons have come in contact with Mr X, those 1000 persons, after 4-5 days, can undergo the antibody test for screening. However, these 1,000 persons still have to undergo quarantine for 14 days, the incubation period,” he said.
“A positive test in the antibody will tell you that you have been exposed to the virus; and a negative test does not rule out COVID-19 infection, especially if it is very early after exposure. The reliability of such a test, in general, is seven days after the virus has entered the human body. The kit will clearly say what is the probability and at which point it is definite,” Dr Ravi said.
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