The new variant of Covid-19 can spread more rapidly, according to England's chief medical officer, Professor Chris Whitty. However, he stressed that there was currently no evidence that the new strain causes higher mortality rates or affected vaccines and treatments.
Here are answers to some of the key questions about the variant: Is this something unusual? There have been many mutations in the virus since it emerged in 2019.
This is to be expected - SARS-CoV-2 is an RNA virus and these viruses mutate and change. Public Health England (PHE) said that, as of 13 December, 1,108 cases with this new variant had been identified, predominantly in the south and east of England.