Researchers examining the genomes of two people with the coronavirus in Washington State said the similarities between the two cases suggest the virus has been spreading in the state for nearly six weeks, The New York Times reported.
The state had the country’s first confirmed case of the virus Jan. 21, according to the Centers for Disease Control and Prevention. Based on an analysis of the virus’ genetic sequence, researchers said another case announced Friday might have been descended from that first case, the Times reported.
Two new cases were confirmed in Washington’s King County on Sunday, boosting the state total to eight, according to The Washington Post.
Trevor Bedford, an associate professor at the Fred Hutchinson Cancer Research Center and the University of Washington, was one of two scientists who compared the genetic sequences, the newspaper reported. Bedford said the genetic findings suggested the coronavirus had been spreading through other people in the community for nearly six weeks.
“I do think, as more community cases start popping up in the United States, this approach and technique could prove very useful to figuring out the extent of community transmission we currently are having,” Bedford told the Times.
The two people are not known to have had contact with one another, the newspaper reported. Bedford conceded the cases could be unrelated and introduced separately into the United States, but added that seemed unlikely, the Times reported. However, Bedford told the newspaper that in both cases, the virus contained a rare genetic variation that was found in only two of the samples whose sequences have been shared from China.
One scientist, who was not involved in the study, said he agreed with Bedford’s conclusion.
“I think he’s right,” Andrew Rambaut, professor of molecular evolution at the University of Edinburgh, told the Times. “It’s extremely unlikely that two viruses coming from outside the U.S.A. independently would arrive in the same geographical area and be genetically related unless they were connected.”
If the virus has been spreading undetected in Washington since January, it could mean that hundreds already have it, one scientist said.
Mike Famulare, a principal research scientist at the Institute for Disease Modeling in Bellevue, told the Times those people “have either been infected and recovered, or currently are infected now."
Many of those people would now be in the early stages of incubating the virus, and might not yet be contagious, Famulare told the newspaper.
Famulare’s estimate was based on a simulation, the Times reported. He said his numbers were a “best guess, with broad uncertainty.”
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