As India battles the second wave of the Covid-19 pandemic, it still continues to battle misinformation surrounding the deadly virus. The latest among a long list of misinformation is that mutant variants of the coronavirus have the ability to evade RT-PCR tests and thereby produce a "false-negative" result.
In a virtual interaction, Dr Anurag Agarwal, Director, Institute of Genomics and Interactive Biology, IISC, reiterated that such claims were false. During the interaction, he made clear that a swab sample does not make it to the genome sequencing stage unless it is positive for Covid-19, meaning that variants can not produce a false-negative RT-PCR test result.
Dr Agarwal said that coronavirus genomes are regularly sequenced all over the world and reassured that there was no variant that could escape the double gene test.
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He added that the sensitivity of an RT-PCR test is at best 70 per cent, and is most effective when taken a day before symptoms show, owing to the fact that the coronavirus is present in the mouth and nose (where the RT-PCR test samples are obtained from) during this period.
When an individual opts to take a Covid-19 test 7 or 8 days after symptoms show, the virus has travelled deeper inside the body and as a result, one might get a negative result from an RT-PCR test. This, Dr Agarwal said, was not a result of any mutant coronavirus variant, but was something known from the beginning of the pandemic.
RT-PCR tests are considered to be the most reliable way of detecting Covid-19. The Centre had recently asked a few states to up their percentage of RT-PCR tests to detect the virus more effectively.
The Indian Covid-19 variant, also called the double and triple mutants is actually B.1.617 variant of the coronavirus. Many countries including the UK, UAE, and Iran have banned flights from India due to the rise of this variant.