Indian Council of Medical Research (ICMR), the apex body in India for the formulation, coordination and promotion of biomedical research, has validated the first antigen based testing kit in India for diagnosis of COVID-19 in containment zones and healthcare settings in combination with the RT-PCR test.
India is currently performing 1.5 lakh RTPCR tests are being conducted in the country everyday but the testing capacity could go increase significantly using the newly approved technique.
The approved antigen test kits is a rapid chromatographic immunoassay for qualitative detection of specific antigens to SARS-CoV-2. It has been developed by SD Biosensor, a South Korea based company.
Each of the kit (called Standard Q COVID-19 Ag rapid antigen detection test) is priced less than Rs 500 and will be permitted to be used in field conditions. It can show results within 30 minutes as opposed to RTPCR test that takes 3-4 hours once in labs.
Though regraded as gold standard in testing, RTPCR is relatively expensive-- costs Rs 2,500 per testing kit. For the RTPCR tests the samples need to be transported to and then examined at limited number of labs by trained technicians.
Based on two independent evaluations , ICMR determined that the specificity ( (ability to detect true negatives) of the rapid antigen detection test ranged from 99.3 per cent to 100 per cent while Sensitivity of the test (i.e. ability to detect true positives) ranged from 50.6 per cent to 84 per cent . The outcome depended upon the viral load of the patient with higher viral load correlated with higher sensitivity.
In view of its high specificity while relatively low sensitivity, ICMR recommends the use of Standard Q COVID-19 Ag detection assay as a point of care diagnostic assay for testing under (containment zones and healthcare settings) settings in combination with the gold standard RT-PCR test, the advisory said.