On Wednesday, Dec. 1, Dr. Anthony Fauci confirmed to CNN that the U.S. Centers for Disease Control and Prevention identified the first confirmed case of the Omicron COVID-19 variant in the state of California.
Fauci, in addition to confirming the case of infection, said the person was fully vaccinated, but had not received a booster. The patient returned to the United States from South Africa on Nov. 22, he said in the interview.
"The individual was a traveler who returned from South Africa, in November and tested positive on Nov. 29," Fauci said at the White House press briefing.
That individual, Fauci said, is isolated and people close to him were contacted and have, "so far," all tested negative.
During the press conference Fauci reiterated that it was a "matter of time" before the first U.S. case of Omicron was detected, and repeated calls for Americans to get vaccinated and receive booster shots.
The Department of Public Health and the Centers for Disease Control and Prevention in California and San Francisco confirmed that the case was caused by the Omicron variant, with genomic sequencing performed at the University of California, San Francisco, and confirmed by the CDC.
The director of the Pan American Health Organization PAHO, Carissa Etienne, said that "it is likely that other countries will soon begin to see this new variant in circulation."
Brazil, Canada and the United States have already reported cases in recent days, all from people coming from Africa.
"That is why it is important that countries redouble their surveillance efforts, share sequences with the Genomic Surveillance Network of the Americas and report any cases of omicron to WHO," he added.
In the face of the spread of Omicron, the Biden administration plans to enact stricter rules for all incoming travelers, including returning Americans.
The U.S. will require all people entering its territory to be tested one day before boarding their flight, regardless of their vaccination status or country of departure according to The Washington Post.
In addition, travelers could be re-screened within three to five days of arriving in the United States, according to the Washington Post, which cited three federal health officials.