The Kent variant may be up to twice as deadly as previous strains of coronavirus, new research suggests.

The more infectious variant, B117, which swept across the UK at the end of last year before spreading across the world, is between 30% and 100% more deadly, according to a new study.

Epidemiologists from the Universities of Exeter and Bristol said the data suggests the variant is associated with a significantly higher mortality rate among adults diagnosed in the community compared with previously circulating strains.

In the community, death from Covid-19 is still a rare event, but the B117 variant raises the risk

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.”

Researchers looked at death rates among people infected with the new variant and those infected with other strains.

They found that the variant first detected in Kent led to 227 deaths in a sample of 54,906 patients – compared with 141 among the same number of closely matched patients who had the previous strains.

The variant is more transmissible and is thought to have contributed towards the rapid increase in cases before new lockdown rules were introduced across the UK.

According to the study, published in the British Medical Journal, 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 warned 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 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 jab has a similar efficacy against the variant.