A Colorado man is the first in the U.S. diagnosed with a new COVID-19 mutation that United Kingdom officials recently warned was significantly more contagious, according to state officials.

The man, who lives in Elbert County, is in his 20s, with no travel history and no close contacts yet identified, state officials said in a Tuesday news release, adding that a news conference Wednesday morning would provide more details. The man remains in isolation, and contact tracing continues.

A second case in the county is suspected, and both individuals were working in Simla, about an hour northeast of Colorado Springs. Neither are residents of Elbert County, Dwayne Smith, director of public health for Elbert County, told Gazette sister publication Colorado Politics on Tuesday.

“I’m not surprised,” Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, told The Washington Post Tuesday in response to the virus’ arrival in the U.S. “I think we have to keep an eye on it, and we have to take it seriously. We obviously take any kind of mutation that might have a functional significance seriously. But I don’t think we know enough about it to make any definitive statements, except to follow it carefully and study it carefully.”

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El Paso County’s Health Department did not immediately respond Tuesday when asked if the county had seen suspected cases.

The fact that the man had no known travel history or close contacts, according to the state, “suggests there is more than one case in Colorado,” Dr. Elizabeth Carlton, assistant professor at the Colorado School of Public Health and member of the state’s COVID-19 modeling team, said Tuesday.

That variant known as B.1.1.7 is the same one discovered in Europe this month. It triggered alarm when announced by Britain’s prime minister and caused dozens of countries to ban flights from the United Kingdom, as well as strict lockdown measures in southern England. A similar variant emerged in South Africa and potentially Nigeria. It appears to be 70% more transmissible than the dominant strain of COVID-19, Colorado officials said last week.

The World Health Organization has said while the variant might spread more easily from person to person, it isn’t necessarily more dangerous or deadly. A recent briefing on the mutation from England’s health department noted no statistically significant difference in hospitalization or fatality rates, nor in the likelihood of reinfection.

When looking at data on the mutation from the UK, “what’s remarkable is how quickly this new variant took over the region” of eastern England, from being on the periphery to dominating COVID diagnoses within a month, Carlton said.

The COVID-19 virus likely experiences significant mutations once or twice a month, Dr. Sam Dominguez, infectious disease specialist at Children’s Hospital Colorado, told The Gazette last week. Coronaviruses are prone to mutations, he said, adding that the introduction of a vaccine could cause the virus to mutate.

In general Colorado COVID-19 news:

– New infections reported to the state continue generally downward, with 1,158 new cases announced Tuesday — the lowest number since Oct. 21, and down from a peak of 6,618 cases announced Nov. 12.

– As of Tuesday the number of deaths directly caused by COVID was 3,803, while the number of deaths among patients who had COVID at their time of death, including those who died of other causes, was 4,687.

– The percent of individuals tested for COVID-19 whose results return positive was just over 6% Monday, half of what it was in November and early December. The World Health Organization recommended a rate of no more than 5% among communities wishing to reopen this spring.

– Nearly three-quarters of the state’s acute care and intensive care beds were in use as of Tuesday, figures that have held relatively steady after a recent slight decline, according to data. Nearly 40% of adult critical care ventilators were in use Tuesday.