BBC News:- Officials are keeping a close watch on a new descendant of the Delta variant of Covid that is causing a growing number of infections. Delta is the UK's dominant variant, but latest official data suggests 6% of Covid cases that have been genetically sequenced are of a new type. AY.4.2, which some are calling 'Delta Plus', contains mutations that might give the virus survival advantages. Tests are under way to understand how much of a threat it may pose. Experts say it is unlikely to take off in a big way or escape current vaccines. It is not