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How the Rapid Antigen Test Aids Large-scale Testing for Corona at a Fast Pace

Rapid Antigen Test

Perhaps, no one can contest the fact that in a populous country like India with its vast geographical spread, testing for Corona is a gigantic task. Nevertheless, ever since the crisis unfolded, India has remarkably improved its testing capacity both in terms of test numbers and labs. Covid-19 testing capacity has reached to 3 lakh tests per day, with 907 laboratories across India receiving approval to conduct the test.

Beyond this, Indian Council of Medical Research (ICMR), from time to time comes with new interventions that make India’s fight against Corona more effective in terms of quick and early detection of the infection. Rapid Antigen Detection Test for COVID-19 is the recent effort in this regard.

Recently, the Centre stepped in the fray in a big way in Delhi in the fight against Corona after seeing the spike of infections in the national capital. Now the Rapid Antigen Detection Test is mainly being used to go for an aggressive testing drive in Delhi.

What is Rapid Antigen Test?

To put it in simpler terms, it is done by taking only nasal swabs. It is useful in detecting antigens (foreign substances that induce an immune response in the body) which confirms the SARS-CoV-2 virus. Since this does not need an elaborate lab set up, the result comes quick enabling faster detection of the infection.

These excerpts from the ICMR advisory may give you the idea as to how the tests are conducted. “The test can be interpreted as positive or negative after 15 minutes of putting the sample into the well by appearance of test and control lines, which can be read with a naked eye, requiring no specialized equipment. Maximum duration for interpreting a positive or negative test is 30 minutes. After that the test strip should be discarded.”

Is This a Substitute for RT-PCR Tests?

The answer is no. ICMR clearly states “Real time RT-PCR is the gold standard frontline test for diagnosis of COVID19.”

To explain it further, Under Rapid Antigen Test the positive cases need no further test, but there is a scope for false negatives. So, even the cases that are found negative as per the Rapid Antigen Test may actually be found positive as per the RT-PCR test.

The Use of Rapid Antigen Test

ICMR has cleared this to be used in (1) containment zones or hotspots (2) healthcare settings.

In containment zones all Influenza Like Illness (ILI) are to be tested for Covid-19 through Rapid Antigen Test. Also, high-risk contacts with co-morbidities are to be tested under this method.

In healthcare settings, all ILI patients, those who are hospitalised under high-risk group illness, and even asymptomatic patients undergoing aerosol generating surgical/non-surgical interventions like ENT surgery, upper GI endoscopy and dialysis etc. are being tested.

ICMR notes that there are no reliable antigen detection tests available worldwide, which could be used as rapid point of care tests for quick detection of COVID-19 positive patients. In India, it has been developed by SD Biosensor, a South Korea based company, having its manufacturing unit in Manesar, Gurugram. ICMR also said that it encourages other manufacturers / developers who have antigen detection assays to come forward for validation.