from the New York Times by Mike Baker and Sheri Fink
An animation by Nextstrain shows, through genomic sequencing, the spread of the branch of the coronavirus that entered the United States in the Seattle area earlier this year.
Working out of laboratories along Seattle’s Lake Union, researchers from the University of Washington and the Fred Hutchinson Cancer Research Center rushed to identify the RNA sequence of the cases from Washington State and around the country, comparing them with data coming in from around the world.
Using advanced technology that allows them to rapidly identify the tiny mutations that the virus makes in its virulent path through human hosts, the scientists working in Washington and several other states made two disconcerting discoveries.
The first was that the virus brought in by the man from Wuhan — or perhaps, as new data has suggested, by someone else who arrived carrying a nearly identical strain — had managed to settle into the population undetected.
Then they began to realize how far it had spread. A small outbreak that had established itself somewhere north of Seattle, they realized as they added new cases to their database, was now responsible for all known cases of community transmission they examined in Washington State in the month of February.