- Scientists say they have identified a “stealth” version of Omicron that cannot be distinguished from other variants using the PCR tests that public health officials deploy to gain a quick picture of its spread around the world.
- The stealth variant has many mutations in common with standard Omicron, but it lacks a particular genetic change that allows lab-based PCR tests to be used as a rough and ready means of flagging up probable cases.
- Scotland announced a return to working from home where possible until at least the middle of January.
- One major unknown is how the new variant emerged.
According to scientists, a “stealth” strain of Omicron has been discovered that cannot be recognised from other versions using the PCR tests that public health experts use to get a fast picture of the virus’s spread around the world as reported by The Guardian.
Sly variant
The finding came as the number of cases of the original Omicron variant detected in the UK rose by 101 to 437 in a single day and Scotland announced a return to working from home.
The stealth variant has many mutations in common with standard Omicron, but it lacks a particular genetic change that allows lab-based PCR tests to be used as a rough and ready means of flagging up probable cases.
The stealth variant was first spotted among Covid virus genomes submitted in recent days from South Africa, Australia and Canada, but it may already have spread more widely.
Among the seven cases identified so far, none are in the UK.
The discovery came as the prime minister told the cabinet that Omicron appeared to be more transmissible and officials conceded this would have consequences for its impact and the likelihood of further restrictions being needed.
Early indications
At the cabinet meeting on Tuesday, also attended by the government’s chief scientific adviser, Patrick Vallance, and England’s chief medical officer, Chris Whitty, Boris Johnson told ministers the “early indications” were that Omicron was more transmissible than the existing dominant variant, Delta, a No 10 statement said.
Despite such considerations, the spokesperson confirmed that for now, official advice remained that people should return to workplaces if they could, albeit with consideration of mitigations such as ventilation and testing.
Scotland announced a return to working from home where possible until at least the middle of January.
The first minister, Nicola Sturgeon, revealed that about 4% of Covid-19 cases in Scotland were likely to be the Omicron variant, with that figure “steadily rising”.
“Our estimate at this stage is that the doubling time for Omicron cases may be as short as two to three days and that the R number associated with the new variant may be well over 2,” Sturgeon said.
Contact tracing was also being enhanced in Scotland, with close contacts of positive cases told to test and isolate.
Discovery
The discovery of the new form of Omicron prompted researchers to split the B.1.1.529 lineage into standard Omicron, known as BA.1, and the newer variant, known as BA.2.
“There are two lineages within Omicron, BA.1 and BA.2, that are quite differentiated genetically,” Prof Francois Balloux, the director of the University College London Genetics Institute, said.
“The two lineages may behave differently.”
Scientists use whole-genome analysis to confirm which variant has caused a Covid infection, but PCR tests can sometimes give an indication.
One major unknown is how the new variant emerged.
To have two variants, BA.1 and BA.2, arise in quick succession with shared mutations is “worrying” according to one researcher, and suggests public health surveillance “is missing a big piece of the puzzle”.
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Source: The Guardian
