The New York Times – Scientists traced the virus brought to the Seattle area in January. They were astonished to learn that the same branch of the virus traveled on through at least a dozen states and to other parts of the world. “As the coronavirus outbreak consumed the city of Wuhan in China, new cases of the virus began to spread out like sparks flung from a fire. Some landed thousands of miles away. By the middle of January, one had popped up in Chicago, another one near Phoenix…But on Jan. 15, at the international airport south of Seattle, a 35-year-old man returned from a visit to his family in the Wuhan region. He grabbed his luggage and booked a ride-share to his home north of the city. The next day, as he went back to his tech job east of Seattle, he felt the first signs of a cough — not a bad one, not enough to send him home. He attended a group lunch with colleagues that week at a seafood restaurant near his office. As his symptoms got worse, he went grocery shopping near his home. Days later, after the man became the first person in the United States to test positive for the coronavirus, teams from federal, state and local agencies descended to contain the case.

…the arc of the coronavirus’s sweep through the United States would look much different. As it turned out, the genetic building block of the virus detected in the man who had been to Wuhan would become a crucial clue for scientists who were trying to understand how the pathogen gained its first, crucial foothold. 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…”