MOUNT VERNON, Wash. — With the coronavirus quickly spreading in Washington state in early March, leaders of the Skagit Valley Chorale debated whether to go ahead with weekly rehearsal.
The virus was already killing people in the Seattle area, about an hour’s drive to the south.
But Skagit County hadn’t reported any cases, schools and business remained open, and prohibitions on large gatherings had yet to be announced.
On March 6, Adam Burdick, the choir’s conductor, informed the 121 members in an email that amid the “stress and strain of concerns about the virus,” practice would proceed as scheduled at Mount Vernon Presbyterian Church.
“I’m planning on being there this Tuesday March 10, and hoping many of you will be, too,” he wrote.
Sixty singers showed up. A greeter offered hand sanitizer at the door, and members refrained from the usual hugs and handshakes.
“It seemed like a normal rehearsal, except that choirs are huggy places,” Burdick recalled. “We were making music and trying to keep a certain distance between each other.”
After 2 1/2 hours, the singers parted ways at 9 p.m.
Nearly three weeks later, 45 have been diagnosed with COVID-19 or ill with the symptoms, at least three have been hospitalized, and two are dead.
The outbreak has stunned county health officials, who have concluded that the virus was almost certainly transmitted through the air from one or more people without symptoms.
“That’s all we can think of right now,” said Polly Dubbel, a county communicable disease and environmental health manager.
In interviews with the Los Angeles Times, eight people who were at the rehearsal said that nobody there was coughing or sneezing or appeared ill.
Everybody came with their own sheet music and avoided direct physical contact. Some members helped set up or remove folding chairs. A few helped themselves to mandarins that had been put out on a table in back.
Experts said the choir outbreak is consistent with a growing body of evidence that the virus can be transmitted through aerosols — particles smaller than 5 micrometers that can float in the air for minutes or longer.
One of the authors of that study, Jamie Lloyd-Smith, a University of California, Los Angeles infectious disease researcher, said it’s possible that the forceful breathing action of singing dispersed viral particles in the church room that were widely inhaled.
“One could imagine that really trying to project your voice would also project more droplets and aerosols,” he said.
With three-quarters of the choir members testing positive for the virus or showing symptoms of infection, the outbreak would be considered a “super-spreading event,” he said.
