As the Covid-19 virus continues to spread and evolve, each new variant is given an official name—and sometimes an unofficial nickname. We’ll keep this page updated with the latest Covid-19 variant names and an explanation of where the new names come from.
What is XBB.1.5?
XBB.1.5 is a subvariant of the Omicron variant of the Covid-19 virus. In early 2023, medical experts described XBB.1.5 as the most infectious subvariant to date.
🗓 When was XBB.1.5 first observed?
XBB.1.5 was first recorded in the US in October 2022.
Why is it called XBB.1.5?
XBB.1.5 is a sublineage of the lineage XBB, another Omicron subvariant—meaning that XBB.1.5 derived from XBB.
The XBB lineage, which includes XBB.1.5, was categorized by the World Health Organization (WHO) according to the naming system used for the many variants and subvariants of the Covid-19 virus. According to the WHO, the XBB lineage is a subvariant of the Omicron variant and is the result of the recombination of the BA.2.10.1 and BA.2.75 sublineages of Omicron.
Why is XBB.1.5 sometimes called Kraken?
XBB.1.5 is sometimes referred to with the informal nickname Kraken, a reference to the mythological sea monster. This unofficial nickname for the subvariant was first suggested by evolutionary biologist T. Ryan Gregory, who began referring to it as such on Twitter in December 2022 based on his own personal system of nicknaming Covid-19 variants after mythological creatures. The nickname gained use in some media reports about XBB.1.5.
List of Covid-19 variant names
There have been many variants and subvariants of Covid-19. The names of some of the most widespread and prominent ones include:
