The variant which was first reported to the WHO from South Africa on 24 November, has seen a number of new restrictions on travel brought in across much of Europe.
Previously known as B.1.1.529, it has also been identified in Botswana, Belgium, Hong Kong and Israel.
Scientists have raised concerns over its unprecedented series of genetic mutations and the speed in which the variant appears to be spreading.
Daily cases have more than tripled in South Africa since Tuesday, with 2,828 cases recorded on Friday
Maria Van Kerkhove, the WHO’s technical lead on Covid-19, said in a video published on Twitter. “This variant has a large number of mutations, and some of these mutations have some worrying characteristics.”
Despite only being tracked for the past four days, the virus has been identified as having 30 different mutations already. By comparison, that is twice as many as the Delta variant, which has been the most prominent variant in the UK over the past few months.
The mutations contain features seen in all of the other variants but also traits that have not been seen before.
Dr Susan Hopkins, chief medical adviser of the UK Health Security Agency (UKHSA), told BBC Radio 4’s Today Programme: “If we look at those mutations, there’s mutations that increase infectivity, mutations that evade the immune response both from vaccines and from natural immunity, mutations that cause increased transmissibility.
“It’s a highly complex mutation, there’s also new ones that we have never seen before.”
Professor Adam Finn, a member of the Joint Committee on Vaccination and Immunisation (JCVI), told Good Morning Britain on Friday that sequencing is being carried out around the UK to determine if any cases have already been imported.
The UK and Scottish governments and Northern Ireland Executive said on Thursday that UK and Irish residents who arrived in England between midday Friday and 4am Sunday, and who have been in the six countries within the last 10 days, must quarantine at home for 10 days and take NHS PCR tests on day two and day eight, even if they already have a lateral flow test booked.
Passengers – including UK and Irish residents – arriving from 4am Sunday will be required to book and pay for a Government-approved hotel and quarantine for 10 days. They must also take tests on day two and day eight.
Direct flights from the six nations to the UK are being temporarily banned until 4am on Sunday, once the quarantine hotels have been set up.
Since midday on Friday, non-UK and Irish residents who have visited the nations in the previous 10 days have been refused entry into England.
Professor James Naismith, director of the Rosalind Franklin Institute in Oxford, has said the new variant will “almost certainly” make vaccines less effective, though they would still offer protection.
Pfizer/BioNTech, which has produced a vaccine against Covid-19, is already studying the new variant’s ability to evade vaccines.