Colorado's health department discovered the new variant of the coronavirus that may be more transmissible, Gov. Jared Polis announced on Tuesday.

Why it matters: It's the first known U.S. case of the variant, which was initially discovered in the United Kingdom.

• A non-peer reviewed study by the Centre for Mathematical Modelling of Infectious Diseases at the London School of Hygiene and Tropical Medicine found that the variant is 56% more transmissible than other strains.
• The British government previously warned that a new variant could be up to 70% more transmissible.

Of note: There is thus far no evidence that the new variant is more deadly — only that it appears more transmissible. There is also no evidence that COVID-19 vaccines will be less effective against the new variant.

What they're saying: "The health and safety of Coloradans is our top priority and we will monitor this case, as well as all COVID-19 indicators, very closely," Polis tweeted Tuesday.

• According to Polis’ office, the case involves a man in his 20s who has no travel history.
• The man is currently in isolation, and public health officials are doing a “thorough investigation,” the governor’s office added.

The big picture: Dozens of countries banned travel from the U.K. after it discovered the variant.

• Japan announced last week that it would temporarily ban non-resident foreign nationals from entering the country starting on Dec. 28 after it discovered its first case of the new variant.

Go deeper: What you need to know about the coronavirus mutation