The mutant strain of coronavirus, first identified in the UK, remains at low levels in the US, but doubles its range roughly every 10 days, according to a study published by researchers on Sunday.
The study supported modeling by the Centers for Disease Control and Prevention, which last month predicted the more contagious variant could be the dominant strain in the US by March.
The US still has time to take steps to slow the new strain of the virus, the researchers wrote, but they warned that the variant "without" determined and immediate public health action "is likely to have devastating consequences for COVID-19. Mortality and morbidity in the EU will have US in a few months. "
The research, which was partially funded by the CDC and the National Institutes of Health and Canadian Institutes of Health Research, has been published on medRxiv, a preprint server, and has not yet been peer-reviewed.
The new strain of coronavirus, also known as B.1.1.7, spread quickly in the United Kingdom and has become the dominant strain in that country, which by some standards is the hardest hit in Europe.
Health officials have said that existing vaccines are likely to work against new strains, although their effectiveness may be somewhat reduced.
The study found that there are "relatively small" amounts of B.1.1.7. in the US at the moment, but given its rapid spread, it is "almost certainly destined to become the dominant SARS-CoV-2 line by March 2021".
The new strain accounted for 3.6% of coronavirus cases in the United States in the last week of January, according to the study.
Researchers found that tracking the nationwide spread of the strain is made difficult by the lack of a national genomics surveillance program like in the UK, Denmark and other countries.
They wrote that they had "relatively robust" estimates from California and Florida, but that data outside of those states were limited.
The growth rate of the virus was different in the two states, with B.1.1.7. seems to spread a little more slowly in California. The study's authors wrote that the strain doubled roughly every 12.2 days in California, 9.1 days in Florida, and 9.8 days nationally.
The study supports the conclusion that the new strain is already spreading via "significant community transmission".
The authors suggest that the virus was introduced into the country via international travel and spread via domestic travel as millions of Americans crossed the country around Thanksgiving, Christmas, and New Years in the fall and winter.
The authors also found that the variant grew a little slower than in European countries. This is another investigation, but it may be due to the sparse current data or other factors – including "competition from other more portable" variants.
Other strains of coronavirus of concern have been detected in South Africa and elsewhere.
The researchers warned that their results "reinforce" the need for robust monitoring of possible new and emerging coronavirus variants in the US.
"With laboratories in the US only sequencing a small subset of SARS-CoV-2 samples, the true sequence diversity of SARS-CoV-2 is still unknown in that country," they wrote.
"The more established surveillance programs in other countries have issued important warnings of worrying variants that could affect the US, with B.1.1.7 being just one variant that demonstrates the ability to grow exponentially," they added.
"Only with consistent, unbiased, large-scale sequencing that encompasses all geographic and demographic populations, including the often underrepresented, along with continued international scientific collaborations and open data sharing, can we accurately assess and track new variants emerging during COVID-19 Pandemic, "the researchers wrote.
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