According to the World Health Organization, XBB.1.5, nicknamed Kraken, has been detected in 28 countries. It was first detected in the United States in October 2022. They revealed that it is a descendant of the Omicron XBB sub-variant, and its transmissibility has been a cause for concern.

Dr. Maria Van Kerkhove, the technical lead, stated that the variant is responsible for 41% of all infections in the US. She stated that the variant is spreading 40 times faster and called it the most transmissible sub-variant that has been detected yet.

A report published by Bloomberg revealed that higher transmissibility also means more people are likely to get infected and thereby suffer severe outcomes. The report stated that the variants are named in Greek, such as Omicron. The name of the lineage descended from the Omicron is a mix of alphabets and numbers known as "Pango."