There is “some evidence” that the new UK variant of coronavirus may be more deadly than the original strain, the Prime Minister has said.
Mathematicians have produced early findings by comparing death rates in people infected with either the new or the old versions of the virus.
However, Boris Johnson said evidence showed vaccines being rolled out across the UK were working against the variant, which first emerged in the south of England.
Its fast-spreading nature significantly contributed to the decisions to put Scotland and the other UK nations back into lockdown.
More than 600 coronavirus-linked deaths have been registered in Scotland over the past ten days, while 1480 new cases of Covid-19 were reported on Friday, with 2053 people currently in hospital with the virus.
In England, there are currently more than 38,000 people in hospital, with 1401 deaths recorded on Friday.
The Prime Minister told a Downing Street press conference: “We’ve been informed today that, in addition to spreading more quickly, it also now appears that there is some evidence that the new variant, the variant that was first identified in London and the south-east, may be associated with a higher degree of mortality.”
But he insisted the vaccines being rolled out across the UK still appeared to work on the variant.
Johnson said: “All current evidence continues to show that both the vaccines we’re currently using remain effective both against the old variant and this new variant.”
Scientists are concerned the mutant coronavirus strain which emerged in south east England may be more deadly than the original.
The UK’s chief scientific adviser Sir Patrick Vallance said the coronavirus variant which emerged in Kent is “a common variant comprising a significant number of cases” and transmits between 30% and 70% more easily than the original virus.
He told a Downing Street press conference on Friday that among people who have tested positive for Covid-19, there is “evidence that there is an increased risk” of death for those who have the new variant compared with the old virus.
Vallance said: “(For the original version of the virus), if you took a man in their 60s, the average risk is that for a thousand people who got infected, roughly 10 would be expected to unfortunately die … with the new variant, for a thousand people infected, roughly 13 or 14 people might be expected to die.
“That’s the sort of change for that sort of age group.”
His comments come after Professor Neil Ferguson, of Imperial College London, told Robert Peston: “It is a realistic possibility that the new UK variant increases the risk of death, but there is considerable remaining uncertainty.
“Four groups – Imperial, LSHTM (London School of Hygiene and Tropical Medicine), PHE (Public Health England), and Exeter – have looked at the relationship between people testing positive for the variant vs old strains and the risk of death.
“That suggests a 1.3-fold increased risk of death.
“So for 60-year-olds, 13 in 1,000 might die compared with 10 in 1,000 for old strains.
“The big caveat is that we only know which strain people were infected with for about 8% of deaths.”