Days after Boris Johnson said the new strain meant a planned easing of coronavirus rules at Christmas had to be scrapped, genomic researchers found it has already spread around the UK, with cases also identified in Wales and Scotland, as well as England.
Professor Peter Horby, chair of the New and Emerging Respiratory Virus Threats Advisory Group (Nervtag), told an evidence session of the Commons Science and Technology Committee on Wednesday that one theory is the strain may have started from a single person in Kent, and could have been caused by “random errors” when the virus copies.
He added: “The underlying mechanism is not fully clear – it could be because the virus replicates faster, which means you get higher viral loads, which means you are more infectious.
“It could be that it takes a shorter time between being exposed and being infectious – if that timeframe shortens you get quicker transmission.
“Or it could mean the duration of infectiousness is longer.”
Watch: Where is the new coronavirus variant in the UK?
Horby said scientists were still exploring whether the mutant coronavirus strain, which is said to be 70% more infectious than previous strains, could sidestep immunity caused by vaccine or prior infection.
He went on: “What we don’t know yet is if there’s any difference in the severity of disease, the age distribution of cases, or most importantly whether there is any immune escape.”
Horby also denied any suggestion that the prime minister had overstated the transmission rates of the mutant strain in order to cancel Christmas.
He said: “I don’t think there’s been any ‘egging up’, as far as I can tell. This is a new variant which is of concern.”
On Wednesday morning, housing and communities secretary Robert Jenrick played down reports that the government would announce a third national lockdown beginning on Boxing Day.
However, he admitted “it may be necessary to take further action” to contain the spread of the mutant coronavirus.
Speaking at the select committee, Nervtag member Professor Neil Ferguson said data did not suggest a lax attitude towards lockdown measures could have caused the new strain to spread.
He said: “There was nothing special about what was going on in Kent and the south of England during lockdown compared with other areas of the country.
“We saw the non-variant decline in a particular week and place, whilst the variant increased in the same week and place in the same population.”
The Cabinet’s COVID operations committee is meeting on Wednesday to consider the latest data on the spread of the virus, with reports that more of England could be plunged into the new Tier 4 category.
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