Researchers are saying that the highly infectious variant of COVID-19 which was first discovered in Britain is between 30-100% more deadly than previous strains.
The study published in the British Medical Journal compared death rates among people in Britain infected with the so-called UK variant, known as B.1.1.7, against those infected with other strains.
The variant was first detected in Britain September last year.
It has since been found in more than 100 countries and is known to be more transmissible than other previously dominant variants.
Robert Challen, who co-led the research at Exeter University, said threat should be taken seriously due to its high mortality rate, coupled with its ability to spread rapidly.
Meanwhile, a UK parliament committee is assailing England's massive $32 billion test-and-trace program, saying that's made no clear impact on slowing the country's coronavirus outbreak.
Lawmakers on the Public Accounts Committee say the system did not achieved its key goal of avoiding a cycle of national lockdowns.
Dido Harding, who runs the system, is defending the project, saying it's essential and accomplished more than any other comparable European country.
The test and trace system has told 9.1 million people to isolate, according to Harding, and still plays a roll in lifting England's lockdown.