Health authorities from around the world have said the variant does not appear to be more deadly than previously identified Covid-19 strains.
"I'm not surprised", said Dr. Anthony Fauci on Tuesday, about the Colorado discovery.
Newsom did not provide any details about the person who was infected.
"Just an hour or so ago we were informed that this new variant, this new strain, has been identified here in the state of California, in southern California", California Governor Gavin Newsom said in a virtual discussion with top USA infectious disease expert Dr. Anthony Fauci on Wednesday.
Biden also said he plans to invoke the Defense Production Act, which grants the president emergency powers to order expanded industrial output of key materials or products on grounds of national security, to accelerate production of vaccine supplies.
The positive tests were processed at the state lab, which had been on alert for the B.1.1.7. variant since it was first discovered in Britain.
"The virus is becoming more fit, and we're like a deer in the headlights", warned Dr. Eric Topol, head of Scripps Research Translational Institute.
"From what we know from experience with this mutation and other mutations, it's unlikely to have a large impact on vaccine-induced immunity, or existing immunity from previous strains", said Dr. Greg Armstrong, director of the CDC's Office of Advanced Molecular Detection.
The two Guard members had been dispatched on December 23 to work at the Good Samaritan Society nursing home in the small town of Simla, in a mostly rural area about 90 miles outside Denver, said Dr Rachel Herlihy, state epidemiologist.
National Guard members are regularly tested, and neither individual traveled internationally in the weeks prior to getting sick, health officials said.
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Trump, who contracted COVID-19 in October, has often played down the severity of the pandemic and overseen a response many health experts say was disorganized and cavalier and sometimes ignored the science behind disease transmission.
The first man had no known travel history, Gov. Jared Polis said Tuesday.
He has mild symptoms and is isolating at his home near Denver, while the person with the suspected case is isolating at a Colorado hotel, Herlihy said.
Even at such an ambitious rate, it would still take months for the majority of Americans to be vaccinated, he said, adding that the situation may not improve until "well into March".
Colorado officials revealed one confirmed positive case of the new variant, with a possible second case. The CDC said it expects "there will be additional cases that are likely to be detected in the coming days". Almost 338,000 people have died of COVID-19 in the US.
Britain is seeing infections soar and hospitalizations climb to their highest levels on record.
Adm. Brett Giroir, US Health and Human Services assistant secretary, told "Fox News Sunday" officials neither have evidence nor do they believe the vaccine would not be effective against the new variant. But a faster-spreading virus could swamp hospitals with seriously ill patients.
THE US STATE of Colorado has recorded what is reportedly the United States' first case of the new coronavirus variant that was first identified in the UK in recent months.