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CDC says U.K. coronavirus variant could become predominant strain in U.S. by March

Though fewer than 100 cases of the variant have been detected in the U.S., models project "rapid growth" in coming months.
Image: A person gestures while exiting a Disneyland parking lot after receiving a dose of the Moderna COVID-19 vaccine at a mass vaccination site during the outbreak of the coronavirus disease (COVID-19), in Anaheim
A man points to the injection site after receiving a dose of the Moderna Covid-19 vaccine at a mass vaccination site in the Disneyland parking lot in Anaheim, Calif., on Jan. 13, 2021.Mario Anzuoni / Reuters

The U.K. variant of the coronavirus could become the predominant strain in the United States by March, according to a report from the Centers for Disease Control and Prevention published Friday.

So far, only 76 cases of the variant, called B.1.1.7, have been identified in the country, in 10 states, the CDC said.

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But the latest research, which takes into account detailed analyses of scenarios that match the current trajectories of Covid-19 cases, projects that the variant could see "rapid growth" in coming months, putting further strain on the health care system.

"We are very concerned about this variant," said Michael Johansson, one of the study's authors and co-lead of the modeling team for the CDC's Covid-19 response.

Johansson cited evidence from the U.K. that the variant may spread from person to person more readily, and noted the CDC is working to increase efforts to do more testing for such variants in the U.S.

The CDC report comes as the U.S. continues to see cases surpass 200,000 each day. Thursday was the third consecutive day that more than 3,000 people died of Covid-19 in the United States, with a daily total of 3,957. Hospital systems across the country are overwhelmed with Covid-19 patients.

There is no evidence to suggest that the U.K. variant might make people sicker. But a faster spread is sure to lead to more cases overall, the study authors wrote, "exacerbating the burden on an already strained health care system, and resulting in more deaths."

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The variant's increased contagiousness means the U.S. must double down on mitigation strategies, including distancing and masking, as well increasing vaccination rates, the CDC said.

"The increased transmissibility of the B.1.1.7 variant warrants universal and increased compliance with mitigation strategies, including distancing and masking," the study authors wrote.

That includes "higher than anticipated vaccination coverage," the authors wrote. In general, the more transmissible a virus is, the greater the number of people needed to be immune to achieve what is known as herd immunity.

Measles, for example, is highly contagious, and requires an extremely high level of herd immunity to reduce the risk of community spread.

"Back in the spring and summer when experts were speculating based on what we knew at that point about the virus, they were estimating that somewhere about 70 percent of individuals would need to be immune in order to achieve that level of herd immunity," for Covid-19, said Dr. James Cutrell, an infectious disease expert at UT Southwestern in Dallas who was not involved with the CDC report.

"As we've learned more about the virus and refined some of our estimates of how transmissible it is, it's now probably more like 85 percent," he said.

"We know that people are tired and discouraged by what's happened with this pandemic," Johansson said. "But we know that we can act decisively now, and we can turn the corner, and really help prevent another wave coming in the spring."

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