CHENNAI: Tamil Nadu will not use the rapid-antigen testing kits for Covid-19, suggested by ICMR, and will continue to use RTPCR testing, said P Umanath, MD of Tamil Nadu Medical Services Corporation.“It (antigen kits) is not so useful at all. As per the guidelines, one has to do RTPCR test if antigen test comes negative. For a 10 per cent positivity scenario, you will end up doing 10,000 antigen tests and 9,000 RTPCR tests, instead of simply doing 10,000 RT CR tests,’’ he told Express.
What are antigen kits?
As per the ICMR advisory, the kit named StandardQ COVID-19 Ag, is a chromatographic immunoassay for qualitative detection of specific antigens to SARS-CoV-2.It will take 15 minutes to 30 minutes to provide results, unlike an RTPCR kit which take up to 24 hours.With a specificity of 99.3 per cent and 100 per cent, in ICMR’s evaluation, the medical body has told States to use these kits in Covid hotspots.
However, due to the kit’s low sensitivity rate of 50.6 per cent and 84 per cent, ICMR said people who are negative must be re-tested with RTPCR.
Responding to queries from reporters on Monday, Dr Prabhdeep Kaur said the kits will not be required as the State has adequate RTPCR kits, which are superior.While the efficacy of antigen tests are questionable, many States have gone forward with procurement as the price of the kits are low. ICMR has capped the price of antigen kits at `450 while a RTPCR test kit in TN costs upto `3,000.
‘We need antigen testing’
However, some experts say antigen testing is now needed in Tamil Nadu, especially in Chennai, where the positivity rate is around 20 per cent.Infectious Diseases Specialist Dr Subramanian Swaminathan of Gleneagles Global Hospital said if the positivity rate is high, antigen kits must be used. “We should think about investing in it. With faster results, we can isolate people immediately, reducing the transmission rate,’’ Dr Swaminathan said.He pointed out that the procurement cost of an antigen kit is much less than that of an RTPCR kit. “Testing symptomatic cases with antigen tests will be useful,’’ he said.