A new strain of the coronavirus spreading widely in the United Kingdom may already be circulating in the U.S., the Centers for Disease Control and Prevention (CDC) said Tuesday.
The agency in a scientific brief said scientists are working to better understand how easily it might be transmitted, and they do not yet know why it has emerged in the U.K.
“Although a variant may predominate in a geographic area, that fact alone does not mean that the variant is more infectious,” the CDC said.
The CDC noted that even though the strain has not yet been detected in the U.S., it is likely already circulating.
“Ongoing travel between the United Kingdom and the United States, as well as the high prevalence of this variant among current U.K. infections, increase the likelihood of importation. Given the small fraction of U.S. infections that have been sequenced, the variant could already be in the United States without having been detected,” the CDC said.
Viruses have only been sequenced from about 51,000 of the 17 million U.S. cases, the agency said.
Different variants of viruses often emerge or disappear by chance, the CDC said, which may be the case with the U.K. strain — known as VUI 202012/01 for “variant under investigation.”
Alternatively, it may be emerging because it is better fit to spread in humans.
The CDC acknowledged the “rapid change from being a rare strain to becoming a common strain has concerned scientists in the U.K.,” but added “there is no evidence that this variant causes more severe illness or increased risk of death.”
The coronavirus mutates regularly, CDC said, acquiring about one new mutation in its genome every two weeks. Most commercial diagnostic tests are able to detect the virus despite this.
There’s also no indication yet that the new strain interferes with patients’ response to the current coronavirus vaccines.
The CDC, along with state and local health departments, is launching a new surveillance system in January to monitor any genetic changes to the virus strains that have already been identified and sequenced in the U.S.
The new variant has prompted a flurry of travel restrictions aimed at preventing its spread beyond the U.K. However, European Union countries have taken a haphazard approach, resulting in major commercial disruptions. The sudden restrictions have also left many people stranded in airports.
Anthony Fauci, the nation’s top infectious diseases doctor, has advised against blanket travel bans in the U.S. Fauci on Tuesday called the idea “rather draconian,” noting that New York Gov. Andrew Cuomo (D) is also discussing the testing of all arrivals in New York City.
“That’s a big difference than completely shutting off travel and banning travel completely, which is really a rather dramatic step. That’s not really in the cards right now,” Fauci said on “Good Morning America.”
Fauci also said Americans should assume the U.K. strain is “here already.”