Greater Manchester health chiefs have urged anyone who has travelled there from Tier 4 areas or Wales to undergo 10 days self-isolation.
The region's 10 Directors of Public Health said the quarantine should start from December 19 and visitors must remain indoors in the property where they are currently staying.
Other people who live in the house do not need to isolate unless anyone gets symptoms, but no visitors should be allowed in that house at all, even on Christmas Day.
The health chiefs called for the restrictions in official guidance published on Monday evening.
It comes as thousands left London and the South East after it was plunged into Tier 4 restrictions over the weekend.
Dr Jeanelle de Gruchy, director of public health in Tameside, said: "The new strain of Covid, which is increasingly rapidly in tier four areas, is extremely worrying.
"It is incredibly infectious and if you come into contact with someone with this strain you are far more likely to catch it than the original strain.
"We are so concerned about the potential grave impact of this that we have taken the difficult decision to ask anyone who has travelled here for Christmas from any tier four area or Wales to act as if they have this new variant, even if they have no symptoms, and self-isolate for at least 10 days.
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"Other people in the house do not need to self isolate but no visitors should be allowed in that house at all, even on Christmas Day."
She added that they are asking people to follow the same rules households have done when schoolchildren have been asked to isolate after coming in contact with someone who is positive, the Mail Online reports.
The individual is the only one who needs to isolate, but if, during that time, anyone in the house gets symptoms, they must all isolate and the person with symptoms get a test straight away.
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Boris Johnson sparked fury as he cancelled Christmas for 16 million people in London and the South East on Saturday.
He said the restrictions were to stop rising infections rates due to a mutant strain of coronavirus said to be 70% more infectious.
Department of Health statistics show daily infections have risen 64.7 per cent in a week, with today's figure up from the 20,263 posted last Monday.
Deaths are still stable, however, with today's fatality count being 7.3 per cent down on last week's 232.
It comes amid growing fears that millions of families face living under draconian Tier Four restrictions until Easter, with Britain's Covid crisis continuing to escalate.
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