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Hancock announced in a speech to the House of Commons that initial studies have shown that this new variant of the virus could spread quicker.
He added that the UK scientists have notified the World Health Organisation, but there is no evidence so far to suggest that the variant is more dangerous for people who catch it, or resistant to the vaccine.
Hancock also suggested that the new variant of the coronavirus, which has been detected in around 1,000 people, could be the cause of a sudden rise in cases in the South East of England.
He has also announced that London and other areas of the South East will enter into Tier Three regulations from Wednesday.
He said: "Thanks to our genomic capability in the UK, we have identified a new variant of coronavirus.
"Initial analysis suggests this variant is growing faster than the existing variants. we've currently identified over 1,000 cases with this variant, predominantly in the South of England although cases have been identified in over 60 different local authority areas, and numbers are increasing rapidly.
"We've notified the WHO about this new variant and PHE is working hard to continue its expert analysis. I must stress at this point that there is nothing to suggest that this variant is likely to cause serious disease."
He added: "The latest clinical advice is that it's highly unlikely this mutation would fail to respond to a vaccine. But it shows we've got to be vigilant."
As well as London, the Health Secretary announced that parts of Essex and Hertfordshire would also be entering the highest level of coronavirus restrictions.
In Essex, Basildon, Brentwood, Harlow, Epping Forest, Castle Point, Rochford, Maldon, Braintree, Chelmsford, Thurrock and Southend-on-Sea will enter Tier Tree, as well Three Rivers, Watford, Broxbourne, and Hertsmere in Hertfordshire.
He put this down to a significant increase in cases in these areas, as well as in parts of Kent.
The government will announce any other changes to measures on Wednesday, at the agreed formal review date.
Hancock said: "We must act now to shift the curve because... there is not a moment to spare,"
The measures around the South East will come into force at 00:01 on Wednesday morning. It remains to be seen what will be decided for the rest of the country.
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