The first U.S. case of the Omicron coronavirus variant has been confirmed in California, according to health officials.

“The California and San Francisco departments of public health and the CDC have confirmed that a recent case of COVID-19 among an individual in California was caused by Omicron variant,” Dr. Anthony Fauci said Wednesday at a White House press briefing.

The infected person returned from South Africa on Nov. 22., according to the statement. The Omicron variant was first discovered in South Africa around Nov. 18. It has also been confirmed in some European countries.

The CDC said the infected person's symptoms are improving while in self-quarantine. The vaccinated person is experiencing mild symptoms.

The case was confirmed by the California and San Francisco departments of public health through a genomic sequencing that showed the virus dectected was consistent with the Omicron variant.

The Omicron variant was classified as a new variant on Nov. 26.