Authorities are blaming the surge in UK coronavirus cases — which almost doubled in the past seven days — on VUI2020/12/01, a mutant strain.

Early data suggests the new VUI2020/12/01 strain could be “up to 70 per cent more transmissible” than previous COVID-19 strains, according to British Prime Minister Boris Johnson in a televised briefing yesterday.

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Studies suggest the contagious variant first appeared in London’s population in September, and was to blame for 28 per cent of new infections in London and southeast England by mid-November.

However, that figure has worsened, up by 62 per cent by December 9.

Health experts had a raft of warnings about the new strain, which was discovered this week.

“This virus has taken off, it’s moving fast, and it’s leading inevitably to a sharp increase in hospital admissions,” said Patrick Vallance, the government’s chief scientific adviser.

Epidemiologist John Edmunds, part of the government‘s scientific advisory group for emergencies, described the discovery of VUI2020/12/01 as “the worst moment of the whole epidemic”.

“This new variant not only moves fast but it is becoming the dominant variant,” said chief medical officer Chris Whitty.

“It is beating all the others in terms of transmission.”

“There is no current evidence to suggest the new strain causes a higher mortality rate or that it affects vaccines and treatments, although urgent work is underway to confirm this,” Whitty added.

The British government alerted the World Health Organisation about the new strain and expects other countries to stop UK residents from passing through their borders.

Already Scotland has closed its land border with England. The government has also taken extreme measures to stop the virus spreading to other parts of England.

“When the virus changes its method of attack we must change our method of defence,” Prime Minister Johnson said at a news conference Saturday.

“Without action the evidence suggests infections would soar, hospitals would become overwhelmed and many thousands more would lose their lives.”

London has been put into a Tier 4 lockdown – the strictest since March – with household mixing banned and stores forced to close their doors less than a week away from Christmas.

That is despite Prime Minister Johnson saying it would “inhuman” to cancel Christmas just days ago.

— with wires