Just before the busy summer travel season in the US, a new COVID variant called NB.1.8.1—also known as “Nimbus”—is quickly spreading across the world. This version of the virus, which is part of the Omicron family,

NB.1.8.1, a new COVID-19 variant that has caused concern among WHO officials, is now spreading in America, according to CDC data.

Designated as NB.1.8.1, the Nimbus strain is a descendant of Omicron. WHO has listed it among six variants under close observation.