• New York state confirmed its first case of a new, more contagious variant of the coronavirus that was initially discovered in the United Kingdom, Gov. Andrew Cuomo said on Monday.
• The case was identified in a 60-year-old man from Saratoga County who had no travel history, Cuomo said.
• The strain, which has also been found in California, Florida and Colorado, is thought to be more transmissible but doesn't appear to make people more ill.

New York state confirmed its first case of a new, more contagious variant of the coronavirus that was initially discovered in the United Kingdom, Gov. Andrew Cuomo said Monday.

The strain, which has also been found in California, Florida and Colorado, is thought to be more transmissible but doesn't appear to make people more ill or increase the risk of death from Covid-19, experts have said.

The case was identified in a 60-year-old man from Saratoga County who had no travel history, Cuomo said during a conference call with reporters. The man, who is now recovering, worked at a jewelry store where three other people have also tested positive for Covid-19. The state is investigating whether those cases were caused by the new strain.

Cuomo told reporters that the state has conducted about 5,000 tests in search for the new variant, known as B.1.1.7. Cuomo said he believes it's "much more" widespread than people already know.

"If other states could test as much as we were testing and tested for the U.K. strain as much as we've tested, they would be finding them," Cuomo said, adding that officials have yet to detect any cases with the strain in the downstate New York City area.

U.S. health officials have said the variant's arrival in the nation isn't a surprise, though it could make matters worse if it's allowed to spread unchecked. 

While the new variant doesn't appear to cause more severe disease in people who are infected and current vaccines should still work against it, it could lead to more hospitalizations as a result of an increase in cases, U.S. Centers for Disease Control and Prevention said last week. The U.S. is also on alert for a second new, highly infectious strain first found in South Africa, similar to the one in the U.K., CDC officials said.

"Increased infection is a problem, but the increased hospitalization rate is a game changer, because if a hospital capacity is threatened in a region, then that region would have to close down," Cuomo told reporters.

In California, Gov. Gavin Newsom said on Monday that the state has now confirmed six cases of the new variant, all in the southern part of the state. One person in San Diego County has been hospitalized, he said.

"We imagine, in fact, one should just anticipate there will be others identified," Newsom said during a press briefing.

State officials are expected to provide an update by late Tuesday on California's genomic testing, which is being conducted to "understand more comprehensively what this strain looks like and what it's been doing," Newsom said. He said state health officials are carrying out contact tracing efforts.

The CDC now requires all airline passengers traveling to the United States from the United Kingdom to present, before boarding, proof of a negative Covid-19 test taken no more than three days before their departure.

In the U.K. on Monday, Prime Minister Boris Johnson announced a new national lockdown order on England until at least mid-February in hopes of slowing the spread of the new variant. He said the nation's top medical officers believe the strain is between 50% and 70% more transmissible compared with previous versions.

"With most of the country already under extreme measures, it's clear that we need to do more together to bring this new variant under control while our vaccines are rolled out," Johnson said during a televised announcement.

— CNBC's Riya Bhattacharjee contributed to this report.