Amid rising Covid-19 tests, a long wait for RT-PCR tests and the results, concerns over false negative reports are being expressed. It is being speculated that because of the new mutant strains, RT-PCR tests are coming negative, even when a person is actually positive and has symptoms of the infection.
What people should remember is that PCR has a sensitivity of 70 per cent. "The load of the virus in one's mouth and nose remains the highest a day before the symptoms start showing. Then the virus load gradually decreases. If people get tested late after 7 to 8 days, it is possible to get a negative test report because the virus may have travelled inside the body.
Tests coming negative despite symptoms being present is not new and not because of any new strain. This was the case since the beginning, that if delays testing, the test results may come negative.
RT-PCR (Reverse transcription- Polymerase chain reaction) tests are considered the gold standard in the detection of Covid-19 and that is why the Centre is asking all states to increase the percentage of RT-PCR testing, but its sensitivity is not beyond 70 per cent if all tests being done are taken into account.
Double mutant is a new strain formed by two mutated strains. In India, its presence has been found in many states, including Maharashtra and Delhi. E484Q and L452R strains have formed the double mutant.
