A highly infectious variant of Covid-19 that has spread around the world since it was first discovered in Britain late last year is between 30% and 100% more deadly than previous strains, researchers said on Wednesday.
In a study that compared death rates among people in Britain infected with the new SARS-CoV-2 variant, known as B.1.1.7, against those infected with other strains, scientists said the new variant had "significantly higher" mortality.
The B.1.1.7 variant was first detected in Britain in September 2020, and has since been found in more than 100 countries.
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%-70% 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.
"Coupled with its ability to spread rapidly, this makes B.1.1.7 a threat that should be taken seriously," said Robert Challen, a researcher at Exeter University who co-led the research.