First antigen based COVID-19 testing kit approved in India; expected to ramp up testing capacity manifold

NEW DELHI: Indian Council of Medical Research, the body leading the COVID-19 response in the country, has validated the first antigen based testing kit in ndia that will allow infected patients to be diagnosed much faster, at lower rates and without laboratory examinations of the samples.

The development assumes significance as there is widespread concern that not enough COVID-19 tests are being carried out in the country as the testing per million is among the lowest in the badly hit countries.

As of now, nearly 1.5 lakh RTPCR tests are being conducted in the country everyday but the testing could go up significantly using the newly approved technique.

The low testing rates, government officials conceded, are mainly because the current testing method, RTPCR is costly-- at about Rs 2,500 per testing kit-- and for the tests the samples need to be transported to and then examined at limited number of labs by trained technicians.

The antigen test—which can detect presence of molecules of the pathogen that triggers immune response in an infected person—has been developed by a private biotechnology firm SD Biosensor—has also been validated by AIIMS, New Delhi apart from the ICMR and can detect presence of SARS CoV 2 in swab collected from nose alone.

Each of the kit called Standard Q COVID-19 Ag rapid antigen detection test will cost less than Rs 500, can be used in field conditions and can show results within 30 minutes as opposed to RTPCR test that takes 3-4 hours once in labs.

An advisory issued by the ICMR said that the antigen test has a very high specificity (ability to detect true negatives) ranging from 99.3 to 100 per cent while sensitivity of the test (ability to detect true positives) ranged from 50.6 to 84 percent in two independent evaluations, depending upon the viral load of the patient.

In view of the high specificity but relatively lower sensitivity of the antigen test, the ICMR has recommended the kits to be used in  combination with the gold standard RT-PCR test.

“Suspected individuals who test negative for COVID-19 by rapid antigen test should be definitely tested sequentially by RT-PCR to rule out infection, whereas a positive test should be considered as a true positive and does not need reconfirmation by RT-PCR test,” said the advisory.

The agency has also said that the testing kits be used for all symptomatic people with Influenza Like Illness  in containment zones or hotspots, asymptomatic direct and high-risk contacts with co-morbidities of confirmed cases.

In hospitals, the kits are to be used for all symptomatic ILI patients, asymptomatic patients who are hospitalized or seeking hospitalization for chemotherapy and transplants or those who are over 65 years with co-morbidities.

In view of rising demand for testing, ICMR has also asked other manufacturers who have antigen detection assays to come forward for validation.

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