Back'Stealth Omicron symptoms difficult to differentiate from Delta unless…': Expert on sub-variant
What happens in BA.2, an Omicron sub-variant, is that S-gene drop-off doesn't happen with RT-PCRHence if we do not do genome sequencing, we will not be able to differentiate between Delta and this stealth variant
PremiumIn recent findings, it came to light that it is difficult to differentiate between Delta and BA.2, infectious sub-variant Omicron, 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"
Why some reports are coming false negative?
Noting that BA.2 lineage has been found in a substantial fraction in the country, INSACOG earlier this week had also pointed out, “S gene dropout based screening is thus likely to give high false negatives"
“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," it had said.
How severe is BA.2 lineage?
Earlier this week, U.K. health authorities designated BA.2 lineage as a variant under investigation, saying it could have a growth advantage. UKHSA added, they’re investigating a version of the omicron variant based on an increase in the number of cases, but that it’s too early to evaluate its importance or severity.
“It is the nature of viruses to evolve and mutate, so it’s to be expected that we will continue to see new variants emerge as the pandemic goes on," Meera Chand, Covid-19 incident director at the U.K. Health Security Agency.
UKHSA said that 40 countries, including India, had reported BA.2 sequences so far.
Is it more resistant to immunity?
Noting that there is not enough explanation for the rapid growth of the sub-lineage, Anders Fomsgaard, researcher at Statens Serum Institut (SSI), said ‘he was puzzled, but not worried.’
"It may be that it is more resistant to the immunity in the population, which allows it to infect more. We do not know yet," he told broadcaster TV 2, adding that there was a possibility that people infected with BA.1 might not be immune from then catching BA.2 soon after.
"It is a possibility," he said. "In that case, we must be prepared for it. And then, in fact, we might see two peaks of this epidemic."
21 cases of stealth Omicron reported from Madhya Pradesh
This comes at a time when 21 coronavirus cases caused by the Omicron variant's sub-lineage 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."
(With input from agencies)
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