Where did the variant come from?
Public Health England says the coronavirus variant had existed in the U.K. since September and circulated at very low levels until mid-November.
“The increase in cases linked to the new variant first came to light in late November when PHE was investigating why infection rates in Kent were not falling despite national restrictions. We then discovered a cluster linked to this variant spreading rapidly into London and Essex,” the agency said.
Public Health England says there’s no evidence the new variant is resistant to the Pfizer-BioNTech vaccine, which is now being given across the country to high-priority groups such as health care workers.
An article in The BMJ, a British medical journal, says the variant was first detected by Covid-19 Genomics UK, a consortium that tests the random genetic sequencing of positive COVID-19 samples around the U.K. The variant cases were mostly in the southeast of England.
A University of Birmingham professor said in a Dec. 15 briefing that the variant accounts for 20% of viruses sequenced in Norfolk, 10% in Essex, and 3% in Suffolk. “There are no data to suggest it had been imported from abroad, so it is likely to have evolved in the U.K.,” he said.
The variant is named VUI-202012/01, for the first “variant under investigation” in December 2020, BMJ says. It’s defined by a set of 17 mutations, with the most significant mutation in the spike protein the virus uses to bind to the human ACE2 receptor.
“Changes in this part of spike protein may, in theory, result in the virus becoming more infectious and spreading more easily between people,” the article says.
The European Centre for Disease Prevention and Control says the variant emerged during the time of year when people usually socialize more.
“There is no indication at this point of increased infection severity associated with the new variant,” the agency said. “A few cases with the new variant have to date been reported by Denmark and the Netherlands and, according to media reports, in Belgium.”
Mr. Johnson announced tighter restrictions on England’s hardest-hit areas, such as the southeast and east of England, where new coronavirus cases have continued to rise. And he said people must cut back on their Christmas socializing.
“In England, those living in tier 4 areas should not mix with anyone outside their own household at Christmas, though support bubbles will remain in place for those at particular risk of loneliness or isolation,” he said.
A version of this article first appeared on WebMD.com.