Officials confirm first cases of virulent new COVID-19 strain in the U.S. Here's what you need to know.

Colorado Gov. Jared Polis confirmed the state’s first case of the highly contagious COVID-19 variant B.1.1.7 on Tuesday, substantiating fears that the new strain has been spreading in the U.S. undetected. The patient, a 20-something member of the Colorado National Guard, had reportedly been assisting a nursing home hard hit by COVID-19. Officials in Ebert County, where the man is located, now suspect that a fellow guardsman has been hit with a second case.

In a statement, Polis said many questions remain. “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,” said Polis. “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.”

Meanwhile, on Wednesday, California Gov. Gavin Newsom, while speaking online with Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, revealed that the strain had been detected in the state earlier in the day.

The variant, known as B.1.1.7, was first discovered by scientists in the U.K. in September and is believed to contain as many as 23 mutations. The Centers for Disease Control and Prevention notes that it is “associated with increased transmissibility (i.e., more efficient and rapid transmission),” but says there is “no evidence to suggest that the variant has any impact on the severity of disease or vaccine efficacy.”

A new, highly contagious strain of COVID-19 has found its way to United States. (Photo: Michael Ciaglo/Getty Images)
A new, highly contagious strain of COVID-19 has found its way to the U.S. (Michael Ciaglo/Getty Images)

Dr. Amesh Adalja, senior scholar at Johns Hopkins Center for Health and Security, tells Yahoo Life that news of a confirmed case in the U.S. is significant, but not unexpected. “This isn’t surprising,” Adalja says. “We all knew that this virus variant had been here for some time; it’s just that we don’t sequence the way the United Kingdom does,” he adds, referring to the specific test — looking at the virus’s genetic sequence — needed to identify the new strain.

Although the rapid spread of the variant in the U.K. may imply that it was brought in through travel, the first U.S. victim has no history of leaving the country — meaning that it’s spreading on the ground. “I knew that there was likely a domestic chain of transmission of this variant that’s been going on in the United States for some time,” Adalja says.

Fauci shared similar thoughts with Good Morning America on Dec. 22, saying, “When you have this amount of spread within a place like the U.K., you really need to assume that it’s here already.”

Experts are still researching why the strain has proved more contagious, but Adalja says the latest hypothesis is that “individuals with this new variant may have higher viral loads and therefore shed more virus.” Those who are shedding more virus may be more likely to infect others, but the route of transmission remains the same — meaning that precautions such as mask wearing, handwashing and social distancing remain the best ways to prevent its spread.

With the first confirmed U.S. case of the virus, more are likely to follow in the days and weeks ahead, which some fear may force schools and businesses to reevaluate in-person classes or reopening plans. But if there’s one piece of good news amid the troubling arrival of B.1.1.7, it’s that experts feel confident the Pfizer and Moderna vaccines — both of which have been approved by the Food and Drug Administration — will be capable of stopping its spread.

“I think based on the data that we’re seeing that the vaccines are going to be robust against this strain,” says Adalja. “And you have to remember that vaccines don’t just induce one antibody, they induce a whole host of antibodies as well as T-cell immunity. And it’s very hard for a virus to evade a vaccine.”

For the latest coronavirus news and updates, follow along at https://news.yahoo.com/coronavirus. According to experts, people over 60 and those who are immunocompromised continue to be the most at risk. If you have questions, please reference the CDC’s and WHO’s resource guides.

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