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CDC: U.K. Variant Will Be Dominant Strain of COVID-19 in U.S. by March

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Key Takeaways

  • The CDC projects that the U.K. variant will become the dominant strain of COVID-19 in the U.S. by the end of winter.
  • B.1.1.7 is more infectious than the current dominant strain of SARS-CoV-2, the virus that causes COVID-19.
  • The COVID-19 vaccines reportedly work against the new strain.

A new, more infectious strain of COVID-19 that was first detected in the United Kingdom is expected to become the dominant strain of the virus in the United States by March, public health officials recently announced.

Also known as B.1.1.7, the “highly transmissible” strain of SARS-CoV-2 (the virus that causes COVID-19) has already been detected in 10 states in the U.S., according to the Centers for Disease Control and Prevention’s Morbidity and Mortality Weekly Report. Modeling data from the CDC indicates that B.1.1.7 “has the potential to increase the U.S. pandemic trajectory in the coming months,” the report says.

The report also says that B.1.1.7 could rapidly grow in early 2021 and “higher vaccination coverage might need to be achieved to protect the public.” The CDC stresses the importance of universal and increased compliance with safety measures like masking and social distancing to curb the spread of this new strain. The agency notes that it is planning to increase its surveillance program to help identify “variants of concern” in the U.S.

"Taking measures to reduce transmission now can lessen the potential impact of B.1.1.7 and allow critical time to increase vaccination coverage," the report says.

As of January 18, there have been 122 cases of COVID-19 caused by B.1.1.7, according to CDC data.

What This Means For You

While the U.K. variant of COVID-19 is more infectious than the current dominant strain, common prevention methods like social distancing and wearing masks when you're around people from outside your household still prevent this strain of the virus from spreading. Following those strategies, and getting vaccinated when you can, will ultimately lower your risk.

B.1.1.7 Mutation

B.1.1.7 has several mutations, some of which are in the virus's spike protein, the CDC explains, which the virus uses to bind to receptors in your cells to make you sick.

The B.1.1.7 variant has a mutation in the receptor-binding domain of the spike protein. That particular mutation causes an amino acid called asparagine, which is typically found in the original SARS-CoV-2, to be replaced with a different amino acid called tyrosine. As a result, the spike protein is stronger and, it seems, is better able to infect people with the virus.

“Multiple lines of evidence indicate that B.1.1.7 is more efficiently transmitted compared with other SARS-CoV-2 variants circulating in the United Kingdom,” the CDC points out in its Morbidity and Mortality Weekly Report, noting that regions in the U.K. with a higher proportion of B.1.1.7 variants had faster growth of the virus than other areas.

The Future of B.1.1.7

B.1.1.7 has had a rapid growth since it was detected weeks ago. “The numbers of new cases of COVID-19 caused by the U.K. variant are rising most significantly in England, and within England in London in particular,” Prathit Kulkarni, MD, assistant professor of medicine in infectious diseases at Baylor College of Medicine in Texas, tells Verywell. “Preliminary evidence suggests that it is becoming the most dominant strain in this area.”

B.1.1.7 is “likely the dominant strain throughout the U.K. at this point,” Richard Watkins, MD, an infectious disease physician and professor of internal medicine at the Northeastern Ohio Medical University, tells Verywell.

And, as the CDC pointed out, it’s likely to eventually become the dominant strain in the U.S. as well. While B.1.1.7 hasn’t been found to cause more severe infections in people, experts say the high infectiousness of the virus is still concerning for public safety. “More infections will invariably lead to more deaths,” Watkins says.

How To Stay Safe

The good news: Both the Pfizer-BioNTech and Moderna COVID-19 vaccines, which are authorized for use in the U.S., appear to be effective against B.1.1.7. The standard ways of preventing the spread of COVID-19 are also effective against B.1.1.7.

“At this point, the most important thing for the general public to do is to follow the usual core public health precautions, including universal masking and physical distancing outside the home, avoiding large crowds, frequent hand washing, and getting vaccinated as quickly as possible,” Kulkarni says.

Still, Watkins says that public health officials should continue to monitor B.1.1.7. “Ongoing tracking of this and other strains is crucial until we develop herd immunity, either through the vaccine or by infections,” he says.

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