0.17% FALSE NEGATIVES IN THE STATE: DATA

MUMBAI : Amid scepticism over high false negatives in rapid antigen test, the state government data shows that 0.17% of the samples tested in Maharashtra failed to identify Sars-cov-2 virus, which causes Covid-19. At 3.4%, Mumbai suburbs recorded the highest false negative cases in the state.

A false negative is when the antigen test identifies an infected person as negative for the presence of the virus, but the report comes positive in the RT-PCR test. As per rules of Indian Council for Medical Research (ICMR), those with symptoms who test negative for Covid-19 by RAT should be 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.

Since the end of June, 675,035 individuals have undergone tests using antigen kits. Of the 592,167 who tested negative for the virus, 4,235 symptomatic individuals had to undergo a confirmatory reverse transcription polymerase chain reaction (RT-PCR), considered the gold standard. Of these, 1,011 tested positive for the virus in RT-PCR.

“No test provides a 100% guarantee, and this too has its loopholes. Thus, we conduct follow-up RT-PCR tests to rule out any chances of infection. So far, results have been promising. When Delhi started using the kits, there was similar scepticism,” said Dr Pradeep Awate, state surveillance officer.

In Mumbai city, of the 47,931 people who tested negative, 275 (0.57%) turned positive in the RT-PCR test. However, Mumbai suburbs has the highest false negative cases in the state. Of the 5,571 negatives, 194 or 3.4% turned positive in the follow-up test. “Every day on an average, we test over 3,000 people with the kits. False negatives are extremely uncommon. Now, we have also tied up with private labs to provide the facility at home,” said Suresh Kakani, additional commissioner, BMC. “The false negativity rate for RT-PCR is almost 23% but overall, the rate is not even 1%. How is it possible,” asked Dr Abhijit More, who is co-convenor of the Jan Arogya Abhiyaan. A health officer said , “We will soon hold a meeting along with private labs to form parameters to conduct the test.”