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In recent findings, it came to light that it is difficult to differentiate between Delta and Omicron sub-variant BA.2 or so-called stealth variant unless and until genome sequencing is done.
Explaining this, Dr Harsh Mahajan, Founder-Chief Radiologist, Mahajan Imaging told new agency ANI, “What happens in BA.2, an Omicron sub-variant, is that S-gene drop-off doesn't happen with RT-PCR. It's also known as 'stealth variant' as it's similar on thermo fisher RT-PCR kit, to what Delta was"
“Hence if we do not do genome sequencing, we will not be able to differentiate between Delta and this so-called stealth variant or BA.2"
21 cases of stealth Omicron reported from Madhya Pradesh
This comes at a time when 21 coronavirus cases caused by the Omicron variant have been found over the past 18 days in the laboratory of a private medical institute in Madhya Pradesh's Indore. Of this, six are children.
Vinod Bhandari, founder chairman of Sri Aurobindo Institute of Medical Sciences (SAIMS), informed PTI, “Lung involvement ranging from 1 per cent to 50%was observed in six out of 21 patients of this Omicron sub-lineage. Three patients are still hospitalized, while 18 have been discharged. Of the 21, a total of 15 adults have taken both doses of the COVID-19 vaccine."
Why reports are coming false negative for stealth Omicron?
The INSACOG, in its latest bulletin, said while most Omicron cases in the country so far have been asymptomatic or mild, hospitalisations and ICU cases have increased in the current wave and the threat level remains unchanged.
"Omicron is now in community transmission in India and has become dominant in multiple metros, where new cases have been rising exponentially. BA.2 lineage is in a substantial fraction in India and S gene dropout based screening is thus likely to give high false negatives," the INSACOG said.
S-gene drop-out is a genetic variation like that of the Omicron variant.
“The recently reported B.1.640.2 lineage is being monitored. There is no evidence of rapid spread and while it has features of immune escape, it is currently not a variant of concern"
(With input from agencies)
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