Public Health England said that coronavirus variant B.1.617.2, which was first identified in India, would be classified as a variant of concern due to evidence it was more transmissible.
It said that the other characteristics of the variant were still being investigated. "There is currently insufficient evidence to indicate that any of the variants recently detected in India cause more severe disease or render the vaccines currently deployed any less effective," PHE said in a statement.
British Prime Minister Boris Johnson said the government needed to handle carefully the emergence of the variant. "I think we've got to be very careful about that.