The strain, called Delta AY 4.2, has been classified by UK as a variant under investigation (VUI) following evidence that it spreads more quickly than the dominant Delta variant.
So far, it is unclear whether the variant causes a more severe form of Covid or renders the current crop of vaccines any less effective.
As is routine for any new VUI, the UK Health Security Agency (UKHSA) said it is carrying out laboratory and epidemiological investigations to better understand the properties of this variant.
“Viruses mutate often and at random, and it is not unexpected that new variants will continue to arise as the pandemic goes on, particularly while the case rate remains high,” said Dr Jenny Harries, UKHSA chief executive.
“It is testament to the diligence and scientific expertise of my colleagues at UKHSA, and the genomic sequencing capacity developed through the pandemic, that this new variant has been identified and analysed so quickly. However, it should serve as objective evidence that this pandemic is not over,” she said.
New variant accounts for 6% of cases
As of October 20, there were 15,120 cases of AY 4.2, also called VUI-21OCT-01, confirmed by whole genome sequences in England since it was first detected in July.
In the last week, VUI-21OCT-01 accounted for approximately 6 per cent of all Delta cases — confirmed through whole genome sequencing in all nine regions of England.
“The genome of VUI-21OCT-01 does not have many mutations compared to Delta. However, a small change may be enough to cause a difference in the virus properties in some circumstances. UKHSA is monitoring this closely,” the health agency in charge of assessing Covid variants noted.
Britain grapples with fresh surge
Meanwhile, Britain is currently battling the second-highest infection rate in the world, behind the United States, with more than 50,000 cases recorded on Thursday — the highest since July.
On Friday, nearly 50,000 new cases were added, and 180 deaths within 28 days of a positive test, taking the overall toll since the start of the outbreak to 139,326.
High levels of infection among school-age children are said to be responsible for the soaring rates, and have prompted calls for some contingency measures to be reintroduced.
Health secretary Sajid Javid said this week that cases could hit 100,000 a day, as a new advertising blitz was launched to encourage take-up of booster shots and flu jabs.
Concern has been raised about waning immunity levels, given that Britain started its vaccination campaign in December last year, before many other countries.
But the government is resisting calls for masks to be worn in crowded indoor spaces again, even as health officials said it could help cut close-contact transmission and ease the burden on hospitals over the coming winter months.
Ministers say vaccination rates have helped to cut the link between hospital admissions for more serious cases of Covid and deaths.
(With inputs from PTI, AFP)