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.
Sir Patrick 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 ITV’s 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.”
A paper from the New And Emerging Respiratory Virus Threats Advisory Group (Nervtag), published on Friday, said there was a “realistic possibility” that the variant is associated with an increased risk of death but stressed that the “absolute risk of death per infection remains low”.
Sir Patrick cautioned, however, that this is based on evidence which is “not yet strong” and there is “no real evidence of an increase in mortality” among those admitted to hospital with the variant.
He added: “I want to stress that there’s a lot of uncertainty around these numbers and we need more work to get a precise handle on it, but it obviously is of concern that this has an increase in mortality as well as an increase in transmissibility, as it appears of today.”
Dr Susan Hopkins, strategic response director at PHE said evidence was still emerging on the new variant.
She added: “There is evidence from some but not all data sources which suggests that the variant of concern which was first detected in the UK may lead to a higher risk of death than the non-variant.”
Sir Patrick said studies were currently going on to work out why the Kent Covid variant might be more deadly.
Nick Davies, one of the experts behind the increased mortality estimates, said that while it was important to get more evidence “a number of groups have looked at the data in a number of different ways, and unfortunately come to similar conclusions”.
The assistant professor of mathematical modelling at the London School of Hygiene and Tropical Medicine, told BBC Radio 4’s PM programme “we think it could be anywhere between 10% to 50%, according to our analysis”.
Speaking to BBC Radio 4’s PM programme Professor Peter Openshaw, immunologist at Imperial College London, and member of Nervtag, said the higher mortality estimates were “obviously a blow”.
He added: “It has been a bit of a setback really, to find these emerging variants.
“As immunity builds then the fear will be that more of the variants that will emerge in the future could be driven by the escape from the immune pressure that is put on the virus by vaccination and by previous infection.
“The realisation that this virus is capable of relatively fast mutation and development of new variants… has been a bit of a setback for us.”