A mutant covid strain first spotted in the UK back in October is now being blamed for one in every 25 infections across the country.
The XBB 1.5 variant is a type of Omicron and is said to be more infectious as it spreads quickly and appears to evade people's vaccine protection.
Neither of the Omicron strains BQ.1 or XBB have been listed as variants of concern by the UK Health Security Agency.
