In view of this, the Indian Council For Medical Research (ICMR), while arguing that it’s important to scale up testing capacity to the maximum possible levels, has invited manufacturers to make rapid antigen kits that are affordable and provide quick results.
Karnataka too, after having used these kits in the Ballari cluster, is looking to procure the same as it ramps up testing capabilities amid growing number of cases. Experts have already advised the government to introduce these kits.
In a meeting last Friday, chief minister BS Yediyurappa was advised that rapid antigen test be conducted for BMTC, KSRTC, ASHA, anganwadi and health workers, police personnel, railway staff, delivery boys, auto and cab drivers among others.
“The gold standard RT-PCR diagnostic test for Covid-19 has limitations in terms of widespread availability. In view of this, there is urgent requirement of reliable and convenient rapid point of care antigen detection assays with high sensitivity and specificity. Such assays could be used as potential diagnostic tests in all possible public and private healthcare settings and made available for mass testing,” the ICMR said.
So far, the council has validated and approved only one rapid antigen detection assay from SD Biosensor, a firm that has branches in Gurugram, China and Korea. “…ICMR invites applications for validation of rapid antigen detection tests for Covid-19 from all manufacturers who have developed such a test,” a notification read.
Dr V Ravi, a virologist at Nimhans and member, Karnataka Covid technical committee, explained: “Unlike antibody kits, which measure a body’s response to the virus and are not diagnostic, antigen tests will tell us if a person is positive or not. RT-PCR, for example, detects the virus’ genetic material, the antigen tests detect the virus’ protein. In the case of SARS-CoV-2, it would be the S-protein.”
He said that antigen tests have an accuracy of 50% to 80% of RT-PCR positive samples, which means that if a test comes positive on the antigen kits, there would be no need for an RT-PCR test, but in case it shows negative, the sample will have to be re-confirmed through an RT-PCR test.
“It is a very simple test that needs no sophisticated labs or trained personnel. You collect the samples and place it on a strip — like a pregnancy kit — and wait for the line. In about 20 minutes, it will tell you if it is positive or not,” Ravi added.
He said that while there is a huge demand for antigen kits, the fact that there’s only one approved firm may delay procurement. “But it is good that ICMR has invited other companies to also get their kits validated,” Ravi said.