SEATTLE — 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. Two others came down in the Los Angeles area. Thanks to a little luck and a lot of containment, those flashes of the virus appear to have been snuffed out before they had a chance to take hold.
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. Sixty-eight people — the ride-share driver at the airport, the lunchmates at the seafood restaurant, the other patients at the clinic where the man was first seen — were monitored for weeks. To everyone’s relief, none ever tested positive for the virus.
But if the story ended there, 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.
And it had jumped.
A genetically similar version of the virus — directly linked to that first case in Washington — was identified across 14 other states, as far away as Connecticut and Maryland. It settled in other parts of the world, in Australia, Mexico, Iceland, Canada, the United Kingdom and Uruguay. It landed in the Pacific, on the Grand Princess cruise ship.
The unique signature of the virus that reached America’s shores in Seattle now accounts for a quarter of all U.S. cases made public by genomic sequencers in the United States.
With no widespread testing available, the high-tech detective work of the researchers in Seattle and their partners elsewhere would open the first clear window into how and where the virus was spreading — and how difficult it would be to contain.
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