The Covid-19 vaccine developed by Pfizer and BioNTech is likely to protect against a more infectious variant of the virus, which was discovered in Britain and has spread around the world, according to results of further lab tests released on Wednesday.

British Prime Minister Boris Johnson has said a variant of the coronavirus, which could be up to 70% more transmissible, is spreading rapidly in Britain. A separate variant, first found in South Africa, is also causing concern.