By Michael Balsamo and Zeke Miller

A person in California who had been vaccinated against COVID-19 became the first in the U.S. to have an identified case of the omicron variant, the White House announced Wednesday as scientists continue to study the risks posed by the new virus strain.

Dr. Anthony Fauci told reporters the person was a traveler who returned from South Africa on Nov. 22 and tested positive on Nov. 29. Fauci said the person was vaccinated but had not received a booster shot and was experiencing “mild symptoms.”

The Biden administration moved late last month to restrict travel from Southern Africa where the variant was first identified and had been widespread. Clusters of cases have also been identified in about two dozen other nations.

“We knew that it was just a matter of time before the first case of omicron would be detected in the United States,” Fauci said.

He said the person was improving and added, “I think what’s happening now is another example of why it’s important for people to get vaccinated. But also boosting. Boosting is very important.”

Officials said they had contacted everyone who had close contact with the person and they had all tested negative.

Genomic sequencing was conducted at the University of California, San Francisco and the sequence was confirmed by the Centers for Disease Control and Prevention.

The Centers for Disease Control and Prevention is taking steps to tighten U.S. testing rules for travelers from overseas, including requiring a test for all travelers within a day of boarding a flight to the U.S. regardless of vaccination status. It was also considering mandating post-arrival testing.

Officials said those measures would only “buy time” for the country to learn more about the new variant and to take appropriate precautions, but that given its transmissibility its arrival in the U.S. was inevitable.

Much remains unknown about the new variant, including whether it is more contagious than previous strains, whether it makes people more seriously ill, and whether it can thwart the vaccine. Fauci, the top U.S. infectious disease expert, said more would be known about the omicron strain in two to four weeks as scientists grow and test lab samples of the virus.

California’s Department of Public Health credited the state’s “large-scale testing and early detection systems” for identifying the case.

“We recognize that everyone is exhausted, and the news of a new variant can be overwhelming. It is important that we collectively focus on the things we know prevent the spread of COVID-19, and its variants,” state public health officials said in a statement.

The announcement of the first U.S. case comes before President Joe Biden plans to outline his strategy on Thursday to combat the virus over the winter. Biden has tried to quell alarm over the omicron variant, saying it was a cause for concern but “not a cause for panic.”

Biden and public health officials have grown more urgent in their pleas for more Americans to get vaccinated — and for those who have been vaccinated to get booster shots to maximize their protection against the virus.

Updated on December 1, 2021, at 3:45 p.m. ET with the latest details.

Share:
More In Science
Our Biological Connections With Plants; Mind-Controlled Bionic Hand
On this episode of Cheddar Innovates: Brightseed Co-Founder breaks down what plant bioactives are, and how they're using the latest technology to study human's biological connections with plants; Esper Bionics CEO breaks down how they re creating a mind-controlled bionic hand that guest smarter the more you use it; Cheddar gets a look at Curiosity Stream's 'Capturing A Black Hole In Our Milky Way.'
NOAA Predicts Busier-Than-Usual Hurricane Season
Hurricane climatologist Jill Trepanier joined Cheddar News to discuss NOAA's announced prediction for an above-normal hurricane season and what it might mean for people in the United States. "I think it's important that people who maybe haven't been used to having extreme weather events related to say tropical cycles and tropical systems, like thinking New Jersey, Northeastern seaboard, that area may get more action than they're used to in the past," she said.
Miga Health Raises $12 Million to Combat Heart Disease
Dr. Jarrad Aguirre, Co-Founder and CEO of Miga Health, joins Cheddar News' Closing Bell, where he says his company is looking to establish the future of heart health and points to how 80% of premature heart attacks and strokes are preventable.
Cooling the Earth; How Global Warming will Impact Real Estate
On this episode of Cheddar Reveals, David Keith, Professor of Applied Physics at the Harvard School of Engineering and Applied Sciences and Professor of Public Policy at the Harvard Kennedy School, and founder of Carbon Engineering outlines the viability of solar geoengineering as a solution to help reverse the effects of global warming; Lena Geraghty, Sustainability & Urban Innovation Director at National League of Cities, discusses which U.S. cities are safest from global warming and how the real estate market will be impacted from the effects of climate change; Cheddar gets a look at Curiosity Stream's 'Changing Ocean Asia.'
Artificially Cooling the Planet
David Keith, Professor of Applied Physics at the Harvard School of Engineering and Applied Sciences and Professor of Public Policy at the Harvard Kennedy School, and founder of Carbon Engineering joins Cheddar Reveals to outline the viability of solar geoengineering as a solution to help reverse the effects of global warming.
Global Warming's Effect on the Real Estate Market
Lena Geraghty, Sustainability & Urban Innovation Director at National League of Cities, joins Cheddar News to discuss which U.S. cities are safest from global warming and how the real estate market will be impacted from the effects of climate change.
What Spending 665 Days in Space Feels Like
Peggy Whitson, Director of Human Space Flight, Axiom Space, joins Cheddar Innovates to discuss Axiom's involvement in the first fully-private mission to the ISS, and her experience spending 665 days in space.
Living in Outer Space; A New-Age Twist on Millenia-Old Remedies
On this episode of Cheddar Innovates, Peggy Whitson, Director of Human Space Flight, Axiom Space, breaks down Axiom's involvement in the first fully-private mission to the ISS, and her experience spending 665 days in space; William Li and Danielle Chang, co-founders of The Hao Life, discuss how they're shaking up the $71 billion supplement industry by putting a modern spin on traditional natural Chinese remedies; Cheddar gets a look at Curiosity Stream's 'Sagrada Familia: Gaudi's Challenge.'
Load More