Rapid tests may be masking TS’ Covid-19 picture

Telangana state, over the past week or so, has dramatically improved its Covid-19 testing numbers from a high of around 6,000 till July 9 to 15,000-plus as on July 17, thanks to introduction of rapid antigen tests (RATs).

Though the testing numbers, it also hides a secret: The absence of retesting the RAT-negative individuals using the RT-PCR (reverse transcription polymerase chain reaction) tests as advised by the Indian Council for Medical Research (ICMR).

This in turn, is believed to be resulting in lower positive test results which hides the true extent of Covid-19 spread.

Though the ICMR advised advised RATs as point of care diagnostic tests, it had said that the RAT test kits’ ability to detect true positives had ranged from 50.6 to 84 per cent in two independent evaluations, depending upon the viral load of the patient. “Higher viral load correlated with higher sensitivity,” the ICMR said in its advisory on using these kits. The ICMR further said “suspected individuals who test negative for Covid-19 by the rapid antigen test should be definitely tested sequentially by RT-PCR to rule out infection, whereas a positive test should be considered as a true positive and does not need reconfirmation by RT-PCR test.”

It is reliably learnt that those testing negative in the RATs state are not being tested using the RT-PCR test as they are leaving the primary health care centres and other locations where these kits are being used as they are not keen on taking another test.

As per data released by the state health department on Friday, the positivity rate among those being tested stood at 18 per cent.

The department, in its

Covid-19 bulletin since it began using RATs around July 10, has never differentiated the number of Rt-PCR, RATs, TrueNat & CBNAAT tests, (the latter two typically used to test for tuberculosis but repurposed for testing for

Covid-19).

This, according to doctors, leaves a huge question mark on the number of true positive Covid-19 cases as no information is being released by the health department on how many RATs are being conducted each day, how many of these results are positive and whether those testing negative are being retested using the RT-PCR tests.

It is believed that if the state follows ICMR guidelines properly with respect to RATs, then the daily Covid-19 case load will show a significant increase.