A mutated form of Covid-19 may now account for up to two in five cases in parts of England, research shows.
Officials designated the strain AY.4.2, nicknamed Delta Plus, a ‘variant under investigation’ on October 20.
Scientists have said it may spread more easily than the standard Delta strain, but there is no evidence that it cause more serious illness.
There is also no evidence that the three Covid vaccines used in the UK are any less effective against the new strain.
Preliminary findings from the Wellcome Sanger Institute, one of the research bodies that works with the UK Health Security Agency (UKHSA), show potential hotspots for the new variant.
Its researchers analysed more than 26,000 positive Covid-19 tests from the week to October 30.
Mid-Devon was found to have the highest proportion of Delta Plus cases, at 42%, followed by Torridge in North Devon at 41% and Milton Keynes at 37%.
The research is provisional, but gives more localised detail than the official figures published by the UK Health Security Agency (UKHSA).
The UKHSA’s figures show Delta Plus accounted for 11.3% of cases in England in the week to October 24.
The South East has England’s highest rates of Delta Plus, accounting for 19.5% of cases on October 25.
Dr Jenny Harries, the agency’s chief executive, said: “The public health advice is the same for all current variants.
“Get vaccinated and, for those eligible, come forward for your third or booster dose as appropriate as soon as you are called.
“Continue to exercise caution. Wear a mask in crowded spaces and, when meeting people indoors, open windows and doors to ventilate the room.
“If you have symptoms take a PCR test and isolate at home until you receive a negative result.”
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