The mutation is also found in the variants identified in South Africa and Brazil. Scientists believe it enables the virus to escape antibodies produced by the body, after either immunization or a previous coronavirus infection. Vaccines and certain antibody drugs might therefore not work so well.
Eleven cases of the variant, called B.1.1.7, had the E484K mutation in a data set of more than 200,000 sequences in the UK, Public Health England said on January 26.
Lawrence Young, a virologist at the University of Warwick, said the mutation was a "concern".
The fact that the variant found in the UK appears to be acquiring this mutation "shows that the virus is very likely to be adapting to our immune response," he said.
The variant identified in South Africa "might be able to more efficiently re-infect individuals who have previously been infected with the original form of the virus," he said in a statement.
"This is likely to be due, in part, to the E484K mutation which may weaken the immune response."
He said the mutation could also affect how long the antibody response lasts.
The variant detected in the UK has been sequenced in 55 countries, including the US. There are at least 342 cases in the US, according to reports based on GISAID data.
The vaccine maker Novavax said on Thursday that its vaccine was found to be less effective for the variant found in South Africa. Johnson & Johnson said on Friday that its shot was found to be less effective in South Africa - scientists have suggested that this was because of the E484K mutation.
Pfizer and Moderna have both said that their vaccines work, albeit slightly less well, against man-made lab variants that contain the mutation. Neither company has tested against real-world coronavirus variants.
"If this E484K mutation is acquired by most of the UK B.1.1.7 variants, the recent reassurances from recent studies showing that the mRNA vaccines" - like those from Moderna and Pfizer - "will still offer optimum protection against the original UK variant may no longer apply," Julian Tang, a clinical virologist at the University of Leicester, said in a statement.
It "is a worrying development, though not entirely unexpected," Tang said.
Simon Clarke, an associate professor in cellular microbiology at the University of Reading, said that while no assessments had been made about the effectiveness of the vaccines in use in the UK - from Pfizer and AstraZeneca - they might work less well against B.1.1.7 variants with this mutation.
Mutations happen when a virus replicates and makes errors; this is a normal process. But mutations become worrying when they affect the virus' behaviour.
Public Health England said preliminary information suggested that more than one "acquisition event" had caused the E484K mutation.
It could also have come about because someone was infected with both a variant identified in South Africa or Brazil as well as the variant found in the UK, Tang said. This is seen with flu viruses but is rarer with coronaviruses, Tang added.
Young said that whatever changes had occurred in the B.1.1.7 or any other virus variant, standard measures to restrict transmission - handwashing and social distancing, for example - would help to prevent infection.
This article was originally published by Business Insider.