ICMR GUIDELINES PUSH ANTIGEN TESTS AMID SURGE

NEW DELHI: The Indian Council of Medical Research (ICMR) on Tuesday issued a fresh Covid-19 testing advisory that recommends using more rapid antigen tests (RAT) in the wake of exponential surge in cases that has overwhelmed the country’s health care delivery system, and caused huge backlogs in the gold-standard RT-PCR tests. While ICMR is counting on more reliable new-generation RAT kits, if the tests end up being as inaccurate as the previous generation of RATS, they could artificially lower Covid-19 case numbers, and potentially create undiagnosed superspreaders.

“The best public health action is to help people know about their status at the earliest, even if somebody is asymptomatic; and laboratories performing reverse transcription polymerase chain reaction (RT-PCR) tests are functioning to their full capacity. So, why should one wait for two to three days to get their confirmatory test result to come back?” asked Dr Samiran Panda, head, epidemiology and communicable disease, ICMR.

To be sure, ICMR’S decision seems to be driven by two factors: new-generation RATS that are more accurate; and the fact that their use has always been recommended when time is a constraint (and in the current context, it is). If time is not a constraint, the use of RT-PCR tests is recommended because RATS tend to have a high proportion of false negatives, identifying infected people as uninfected. During the first wave, many states depended on RATS when they were constrained by testing capacity (not time), which is not recommended.

“The companies try to come up with modified kits that are of higher sensitivity and specificity. The current RAT kits that have been evaluated by us, these have been tested to see how they perform in symptomatic individuals and asymptomatic individuals,” Dr Panda added.