The highly-infectious Covid-19 variant has entered the US as the state of Colorado reported the first known case.
The patient, a man in his 20s, is currently in isolation. He has no travel history.
State health officials said they were working to identify contacts and other potential causes of the new variant.
The US has also recorded more than 19 million coronavirus cases and more than 337,000 deaths.
Experts say that the new variant is more transmissible than the previous types. But not necessarily any more dangerous for those infected, experts say.
US health officials said last week that they believed it was already in circulation in the country.
Colorado governor Jared Polis said the infected patient was in isolation in Elbert County near Denver.
He added that public health officials were carrying out “a thorough investigation”, and no infections had been discovered among close contacts so far.
The new case came as President-elect Joe Biden slammed the Trump administration over the distribution of the vaccine.
He had also said that the vaccine drive was the “greatest operational challenge we’ve ever faced as a nation”.
“The Trump administration’s plan to distribute vaccines is falling far behind,” Mr. Biden said in a speech on Tuesday. “I’m going to move heaven and earth to get us going in the right direction.”
President Donald Trump responded in a tweet that it was “up to the states to distribute the vaccines” once they had been delivered by the federal government.
“We have not only developed the vaccines, including putting up money to move the process along quickly, but gotten them to the states,” he wrote.
Newly-elected US lawmaker dies from Covid
A newly-elected US lawmaker has passed away due to coronavirus.
Republican Luke Letlow, 41, had been elected as Representative for Louisiana’s 5th district and was due to be sworn in on Sunday.
I hope all of the people of Louisiana will join Donna and me in praying for Congressman-elect Letlow’s family, especially his wife Julia and their two children, his many friends, and the people of the 5th Congressional District. #lagov
— John Bel Edwards (@LouisianaGov) December 30, 2020