“If I were to guess, I’d say it’s probably in the hundreds by now,” said Michael Verbobe, head of the Department of Ecology and Evolutionary Biology at the University of Arizona. “It is very possible that it arrived at many places multiple times.”
“Imagine the amount of infected travelers going to London – which is growing rapidly,” said Trevor Bedford, Associate Professor of the Vaccine and Infectious Diseases Division of the Fred Hutchinson Cancer Research Center.
British scientists have detected the earliest known presence of the new strain in Kent, a county southeast of London, on 20 September.
Warobe and Bedford say they anticipate the virus may have arrived in the US in mid-November.
Both scientists, as well as others around the world, have looked at genetic sequences of coronoviruses in the United States to see if one coincides with the UK version. So far, they have not found any, but they say there is a possibility because the US surveillance system is not catching them.
Health officials agree.
“You really need to assume that it is already here, and certainly not the major stressor, but I wouldn’t be surprised at all if it is already here,” National Institute of Allergy and Infectious Diseases Director Dr. Anthony Fauci, said on Tuesday.
Health Admiral Brett Giroir said on Monday, “It could happen in the United States and we have yet to find it.”
The UK coronavirus version has not been identified through sequencing efforts in the United States, the US Center for Disease Control and Prevention said in a scientific brief post on its website on Tuesday.
However, it says, out of 17 million US cases, only about 51,000 have been told that they have been indexed – less than half a percent.
“Given the small fraction of American infections, the variant can already be found in the United States,” the CDC said.
To detect new mutations of the virus, samples are collected from infected patients and then undergo genetic sequencing, looking at the sequence of letters in its genetic code to try something new.
In the US, only a relatively small number of samples undergo this process.
Since November 15 – about the time of the arrival of US variants in the UK – genetic sequencing has been performed on the virus found in about 300 people in the United States and about 9,000 in the UK, Vorbe said.
“We’re flying blind,” Warboe said. “Maybe some other similarly interesting versions are uplifting with higher frequency, but we’re not seeing that.”
This difference is particularly in view of how many infections have been confirmed in the US – compared to over 2.1 million in the UK.
Last month, the CDC launched a stress monitoring program, where states would send at least 10 samples for analysis for biosynthesis. The agency expects the program to be fully implemented in January.
Michael Nedelman of CNN contributed to this report.