The United States reported its first confirmed case of a highly infectious coronavirus variant on Tuesday.
It was discovered in a patient in Colorado, and came as President-elect Joe Biden criticized the current administration's vaccination rollout.
Biden warned it could take years for most Americans to be vaccinated at the rate they're being distributed now.
About 2 million people have been vaccinated - well short of the 20 million promised by outgoing Republican President Donald Trump by the end of the year.
"The Trump administration's plan to distribute vaccines is falling behind, far behind."
Shortly after his remarks in Delaware, Colorado Governor Jared Polis confirmed the first case of the coronavirus variant, the same variant first detected in Britain.
The infected patient was a man in his 20s with no recent travel history and is currently in isolation, Polis said in a statement. His office said no close contacts to the individual have been identified so far.
Scientists believe the variant is more contagious than others.
So far, the variant reared its head in a number of European countries, Canada, Australia, India, South Korea and Japan, among others.
Biden is set to assume the presidency on January 20 and said his administration will prioritise a speedy vaccine rollout, expanding testing and funding states to help reopen schools safely.