The UK strain of Covid-19 which has spread across the world could be up to twice as deadly as previous variants.
The more infectious B117 variant, also known as the Kent variant, which swept across the UK at the end of last year, is between 30 per cent and 100 per cent more deadly, according to a new study.
The study compared death rates among people in Britain infected with the new variant against those infected with other strains. Epidemiologists from the Universities of Exeter and Bristol said the new highly infectious variant had "significantly higher" mortality.
The B117 variant was first detected in Britain in September 2020 and has since been found in more than 100 countries. It is thought to have contributed towards the rapid increase in cases before new lockdown rules were introduced across the UK.
It has 23 mutations in its genetic code – a relatively high number of changes – and some of these have made it far more able to spread. UK scientists say it is about 40 per cent to 70 per cent more transmissible than previously dominant circulating coronavirus variants.
In the UK study, published in the British Medical Journal on Wednesday, infection with the new variant led to 227 deaths in a sample of 54,906 Covid-19 patients, compared with 141 among the same number of patients infected with other variants.
Robert Challen from the University of Exeter, lead author of the study, said, “In the community, death from Covid-19 is still a rare event, but the B117 variant raises the risk.
“Coupled with its ability to spread rapidly, this makes B117 a threat that should be taken seriously.”
According to the study, the higher transmissibility of the Kent strain meant that more people who would previously have been considered low risk were admitted to hospital with the newer variant.
Leon Danon from the University of Bristol, senior author of the study, said, “We focused our analysis on cases that occurred between November 2020 and January 2021, when both the old variants and the new variant were present in the UK.
“This meant we were able to maximise the number of ‘matches’ and reduce the impact of other biases. Subsequent analyses have confirmed our results.
“Sars-CoV-2 appears able to mutate quickly, and there is a real concern that other variants will arise with resistance to rapidly rolled-out vaccines.
“Monitoring for new variants as they arise, measuring their characteristics and acting appropriately needs to be a key part of the public health response in the future.”
Ellen Brooks-Pollock from the University of Bristol said, “It was fortunate the mutation happened in a part of the genome covered by routine testing.
“Future mutations could arise and spread unchecked.”
In January, a paper from the New And Emerging Respiratory Virus Threats Advisory Group (Nervtag) said there was a “realistic possibility” that the variant was associated with an increased risk of death.
But scientists stated there was a lot of uncertainty around the data.
Mutations of the virus have raised concerns about whether vaccines would be effective against the new strains, including the now-dominant Kent strain.
But research suggests the Pfizer-BioNTech jab is just as effective against the Kent variant of coronavirus as it was against the original pandemic strain, while other data indicates the Oxford-AstraZeneca vaccines has a similar efficacy against the variant.