A new sub-lineage of the highly contagious Delta variant that is spreading throughout the UK has been detected in the United States, health officials said Wednesday.

AY.4.2 is being closely monitored in the UK after British health officials revealed that the new variant — reported to be 10 to 15 percent more transmissible that Delta — had been linked to a growing number of COVID-19 infections there.

She added: “In the United States, Delta remains the dominant variant with more than 99.7% of sequence cases in the country being caused by Delta.”.

British health officials said last week they were closely monitoring AY.4.2 after the latest data showed 6 percent of COVID cases in the country were linked to the new variant.