A person in California has the nations first confirmed case of the new omicron coronavirus variant, the Centers for Disease Control and Prevention announced Wednesday.

The unidentified individual was a traveler who returned from South Africa to the U.S. on Nov. 22. The case was confirmed by the California and San Francisco departments of public health, according to the CDC.

The individual, who was fully vaccinated and had mild symptoms that are improving, is self-quarantining and has been since testing positive. All close contacts have been contacted and have tested negative, the CDC said in a statement.

The traveler, who is a San Francisco resident, developed COVID-19 symptoms on Nov. 25 and got tested on Nov. 28, revealing a positive test result the following day, California Gov. Gavin Newsom (D) said at a press conference Wednesday.