The Omicron variant of COVID-19 has been found in Colorado, the state’s Department of Public Health and Environment announced Thursday afternoon. Gov. Jared Polis and state epidemiologist Dr. Rachel Herlihy confirmed the case was detected in an Arapahoe County woman who had recently traveled to southern Africa. The woman was fully vaccinated, but had not yet received a booster shot.

Colorado is the third state to confirm a case of the variant. The first case detected in the U.S. was a person in Northern California who had recently been to South Africa. The second was a Minnesota man who had returned home from an anime convention in New York City and does not have any links to international travel. All three are experiencing only mild symptoms of the virus, and are isolating at home. Little is known about Omicron, but it has been labeled a “variant of concern” by the World Health Organization.