• The infected individual, a man in his 20s, does not have a history of traveling and is in isolation in Elbert County, about an hour and a half south of Denver, officials said.
• The new strain could be as much as 70% more transmissible.
• U.S. coronavirus vaccine czar, Moncef Slaoui, said earlier in December that the Pfizer and Moderna Covid-19 shots should be effective against new strains.

The first case of a new and potentially more infectious strain of Covid-19 has been confirmed in the United States, Colorado health officials said Tuesday.

The health officials confirmed the case and notified the Centers for Disease Control and Prevention. The infected individual, a man in his 20s, does not have a history of traveling and is in isolation in Elbert County, about an hour and a half south of Denver, officials said.

"There is a lot we don't know about this new Covid-19 variant, but scientists in the United Kingdom are warning the world that it is significantly more contagious," Colorado Gov. Jared Polis said. "The health and safety of Coloradans is our top priority and we will closely monitor this case, as well as all COVID-19 indicators, very closely."

"We are working to prevent spread and contain the virus at all levels," Polis said, adding that public health officials were working to identify other potential cases through contact tracing interviews.

Preliminary analysis of the mutated strain, first identified in the U.K., suggests it may be the culprit behind Britain's recent spike in cases. The new strain, referred to as SARS-CoV-2 VUI 202012/01, could be as much as 70% more transmissible, British Prime Minister Boris Johnson said.

The CDC said in December that the new strain could already be circulating in the U.S. without notice. The CDC cited ongoing travel between the U.K. and the U.S. as an explanation for the potential arrival of the new variant.

Read more: 5 things to know about the new Covid strain spreading in the UK

The discovery of the strain in Britain sparked border closures in European countries like Ireland, France, Belgium and Germany as well as countries outside the continent.

The Trump administration does not plan to impose Covid-19 screenings for passengers arriving at U.S. airports from the United Kingdom, Reuters reported, citing officials familiar with the matter.

The British government confirms that another infectious variant of the coronavirus identified in South Africa has also emerged in the United Kingdom. The strain from South Africa has not yet been identified in the United States.

President Donald Trump's coronavirus vaccine czar, Moncef Slaoui, said earlier in December that the Pfizer and Moderna Covid-19 shots should be effective against new strains.

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