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U.K. COVID Variant Doubles Every 10 Days in the U.S.

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Feb. 8, 2021 -- The coronavirus variant first detected in the United Kingdom is rapidly becoming the dominant strain in several countries and is doubling every 10 days in the United States, according to new data.

The findings by Nicole L. Washington, PhD, associate director of research at the genomics company Helix, and colleagues were posted Sunday on the preprint server medRxiv. The paper hasn't been peer-reviewed in a scientific journal.

The researchers also found that the transmission rate in the United States of the variant, labeled B.1.1.7, is 30% to 40% higher than that of more common lineages.

The findings lend credence to modelling predictions the CDC released in January. The agency said at the time that the new strain could cause more than half of new infections in this country by March, even as the U.S. races to deploy vaccines.

In the new study, while clinical outcomes initially were thought to be similar to those of other coronavirus variants, early reports suggest that infection with the B.1.1.7 variant may increase death risk by about 30%.

A coauthor of the current work, Kristian Andersen, told The New York Times, "Nothing in this paper is surprising, but people need to see it."

Andersen, a virologist at the Scripps Research Institute in La Jolla, CA, said, “We should probably prepare for this being the predominant lineage in most places in the United States by March."

"Our study shows that the US is on a similar trajectory as other countries where B.1.1.7 rapidly became the dominant SARS-CoV-2 variant, requiring immediate and decisive action to minimize COVID-19 morbidity and mortality," the researchers write.

The authors point out that the B.1.1.7 variant became the dominant SARS-CoV-2 strain in the United Kingdom within a couple of months of its detection.

"Since then, the variant has been increasingly observed across many European countries, including Portugal and Ireland, which, like the UK, observed devastating waves of COVID-19 after B.1.1.7 became dominant," the authors write.

The B.1.1.7 variant has likely been spreading between US states since at least December 2020, they write.

As of Sunday, there were 690 confirmed cases of the B.1.1.7 variant in the US in 33 states, according to the CDC. But, the true number of cases is certainly higher. Normal coronavirus tests do not detect if an infection comes from one of the variants. Only genomic sequencing can do that, and the U.S. has only recently begun to ramp up that type of testing.

Washington and colleagues examined more than 500,000 coronavirus test samples from cases across the United States that were tested at San Mateo, CA-based Helix facilities since July 2020.

In the study, they findings of the variant varied across states. By the last week in January, the researchers estimated the proportion of B.1.1.7 in the U.S. population to be about 2.1% of all COVID-19 cases, though they found it made up about 2% of all COVID-19 cases in California and about 4.5% of cases in Florida. The authors acknowledge that their data is less robust outside of those two states.

While those percentages are still low, "our estimates show that its growth rate is at least 35-45% increased and doubling every week and a half," the authors write.

"Because laboratories in the US are only sequencing a small subset of SARS-CoV-2 samples, the true sequence diversity of SARS-CoV-2 in this country is still unknown," they note.

Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota, said the U.S. is facing a "Category 5" storm with the spread of the B.1.1.7 variant as well as the variants first identified in South Africa and Brazil.

"We are going to see something like we have not seen yet in this country," Osterholm said recently on NBC's Meet the Press.

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