Health authorities in Florida have reported finding evidence of a case of a newer, apparently more contagious strain of coronavirus which was first seen in England.
The case, announced by the Florida Health Department, comes after reports in recent days of a number of cases of the UK strain in Colorado and California.
The Florida case was detected in a man in his 20s, with no recent travel history.
It said its experts were working with the Atlanta-based Centers for Disease Control on investigating the case.
The health department did not give further details, such as releasing the man's medical condition or how the strain was detected.
California on Wednesday became the second state to confirm a case of the new virus strain.
The announcement came 24 hours after word of the first reported case of the variant in Colorado - in a National Guardsman who had been sent to help out at a nursing home struggling with an outbreak.
Scientists in the UK believe the variant is more contagious than previously identified strains.
The cases have triggered questions about how the version circulating in England arrived in the US and whether it is too late to stop it now, with top experts saying it is probably already spreading elsewhere in the United States.
The Florida Health Department also tweeted that experts anticipate little to no impact on the effectiveness of the COVID-19 vaccinations being rolled out in a state grappling with overwhelming demand for the vaccines from its large population of elderly people.
State officials reported the highest daily jump in COVID-19 cases ever detected in Florida on Thursday. The state’s Department of Health reported 17,192 new cases and 133 new deaths, raising the toll to 21,857.
Florida Governor Ron DeSantis has said that people 65 and older — more than 4 million of Florida's 21 million population — would be prioritized over essential workers to receive the vaccine. But hospitals and health departments have been struggling to keep up with the demand.
Some people have camped out overnight outside vaccination sites, leading some hospitals to hit pause on scheduling further shots.
DeSantis has begged for patience, saying vaccine supplies are still limited. But the top state official overseeing the vaccine distribution also acknowledged the systems set up for vaccine distribution in the state “aren’t meeting the moment.”
Jared Moskowitz, director of the Florida Division of Emergency Management, said in an interview with the Orlando Sentinel that the state has directed distribution of about 700,000 dosages of the vaccine, but only about a quarter of those have been used so far.
“That tells me there are vaccines sitting in freezers…we want all of our partners to know it’s their jobs to get the vaccine out there,” Moskowitz said.
Moskowitz also expressed frustration with the federal government for sending limited information on the amount of doses that will be sent, which has complicated state planning.