The UK Health and Safety Agency has officially designated the Stealth Omicron mutation for investigation.
A sub-variant of the Omicron mutation, the Stealth Omicron is characterized by some specific genetic defects that make it indistinguishable from other mutations in conventional PCR tests.
British authorities said that the number of domestic and foreign cases is increasing, so it has been designated as an investigational mutation.
In the UK, there were 53 cases of stealth omicrons confirmed on the 10th, and now the number has risen to 426.
Earlier, Danish health authorities said that the stealth omicron mutation, which was 20% of all confirmed cases last month, rose to 45% in the second week of January.