DENVER (NewsNation Now) — Health officials say a Colorado National Guard member has the first reported U.S. case of COVID-19 variant and a second case is suspected in another Guard member.

Dr. Rachel Herlihy, the state’s epidemiologist, said Wednesday that the two were deployed on Dec. 23 to a nursing home with an outbreak of the virus in a small town outside Denver.

She appeared in a virtual briefing with Colorado Gov. Jared Polis, who says the man in his 20s with the confirmed case was recovering in isolation and had mild symptoms.

The variant, known as B.1.1.7, is considered more contagious — a warning health officials in the United Kingdom have been raising since it was first discovered by scientists in the country.

The individual has no travel history and will remain in isolation until cleared by public health officials. Contact tracing is underway to determine who may have been exposed to the Guardsman in Elbert County.

“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.”

The variant is most likely still rare in the U.S., but the lack of travel history in the first case means it is spreading, perhaps seeded by visitors from Britain in November or December, said scientist Trevor Bedford, who studies the spread of COVID-19 at the Fred Hutchinson Cancer Research Center in Seattle.

“Now I’m worried there will be another spring wave due to the variant,” Bedford said. “It’s a race with the vaccine, but now the virus has just gotten a little bit faster.”

Health officials confirmed Wednesday a second suspected case in the state. Both patients were working in the Elbert County community of Simla. Authorities said neither is a resident of the county.

Public health officials are investigating other potential cases of the variant, which was confirmed by the Colorado State Laboratory.

Wednesday, California Governor Gavin Newsrom says the variant has been detected in Southern California.

Scientists in Britain have found no evidence that it is more lethal or causes more severe illness, and they believe the vaccines now being dispensed will be effective against it.

British Prime Minister Boris Johnson reported the weekend before Christmas that the variant was moving rapidly through London and southeast England. The region was placed under strict lockdown measures, and dozens of countries banned flights from Britain. France also briefly barred trucks from Britain before allowing them back in, provided the drivers got tested for the virus.

Japan announced a ban Monday on all nonresident foreigners as a precaution.

New versions of the virus have been seen almost since it was first detected in China a year ago. It is common for viruses to undergo minor changes as they reproduce and move through a population. The fear is that mutations will become significant enough to defeat the vaccines.

South Africa has also discovered a highly contagious COVID-19 variant that is driving the country’s latest spike of cases, hospitalizations and deaths.

Jill Hunsaker Ryan, executive director of Colorado’s Department of Public Health and Environment, said state health officials are using “all the tools available to protect public health and mitigate the spread of this variant.

“The fact that Colorado has detected this variant first in the nation is a testament to the sophistication of Colorado’s response and the talent of CDPHE’s scientist and lab operations,” Ryan said.

The following information comes from CDPHE and describes the genetic differences of this variant:

The Colorado state lab was the first in the country to quickly identify the variant through sophisticated analysis of testing samples. The lab initially performed the diagnostic PCR test on the sample and found that the sample was positive for COVID-19 with strong signals for the N gene and ORF1ab (both are detected when a person has COVID-19), but the signal for the S gene was not detected. When the S gene doesn’t register in the testing, it is called an “S Drop Out Profile,” and it is considered an essential signature for the variant. The sample was flagged for further investigation. Scientists then sequenced the viral genome from the patient sample and found eight mutations specific to the spike protein gene associated with this variant. Genome sequencing is a molecular profiling of the entire viral RNA sequence.

Colorado Department of Public Health and Environment

NewsNation affiliate KDVR and the Associated Press contributed to this report.

• Tracking coronavirus vaccine distribution
• The coronavirus stimulus package has been signed into law. Here’s the latest
• Transition of Power
• Find WGN America on your TV
• Download the NewsNation Now App