NCR cities to roll out rapid antigen tests to scale up Covid-19 surveillance

GURUGRAM: Both Haryana and Uttar Pradesh are set to roll out rapid antigen testing in NCR cities. While Gurugram organised a training session for the new test method on Sunday, Uttar Pradesh announced testing should begin in a few days. This comes three days after home minister Amit Shah had said NCR should respond to the Covid-19 outbreak as a single unit. Delhi had started using rapid antigen tests on Thursday.


“Today’s training session was to familiarise our health workers with the new test that the Indian Council of Medical Research (ICMR) has recommended. We will soon work out the number of kits we need and start procuring them. We are waiting for the government’s guidelines,” said Gurugram chief medical officer Virender Yadav.

In Sunday’s training, attended by 30 participants from 10 Haryana districts, ICMR officials gave a live demonstration of how RADT (rapid antigen detection test) kits work. ICMR had on June 15 approved the use of a rapid antigen test for diagnosis. Swabs are collected from the nose and the test can detect the presence of molecules of the pathogen, specifically, a protein expressed by the novel coronavirus. The test results take about 30 minutes. But while positive results are highly accurate, negatives could be false. So the ICMR has said negative results will need to be confirmed with a second test, a conventional RT-PCR test, before taking a diagnostic call. As point-of-care tests, they do not need a lab setting for the test to be conducted.

In Uttar Pradesh, the rapid antigen tests will kick off from NCR and a few other major cities. “The tests will begin in a few days. They will begin from Noida, Ghaziabad, Lucknow, Kanpur, Varanasi, Gorakhpur and Prayagraj,” additional chief secretary (health and family welfare) Amit Mohan Prasad said on Sunday.

In both states, the antigen tests will be used in containment zones, healthcare settings, on high-risk contacts, immune-compromised patients and the elderly.

The test is very different from the rapid antibody test, which tests blood samples for the presence of antibodies against SAR-COV2, the virus which causes Covid-19. It was used briefly for monitoring and surveillance before being suspended and then started over again for a trial study. But it was strictly not meant for diagnostic purpose, primarily because the presence of antibodies would depend on the timing of the test.

“Specificity (accuracy in detecting true negatives) of the rapid antigen test ranges between 99.3% and 100%, based on validation done at two sites. But its sensitivity (rate of detecting positives correctly) ranges from 50.6% to 84%, based on two independent evaluations. The viral load of the patient may also alter the specificity and sensitivity,” ICMR officials had said last week. Because of the gap in sensitivity, a second confirmatory test has been mandated.