- Sixty people attended the rehearsal on March 10.
- The event is considered a "super spreading" event.
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Forty-five of the sixty people who attended a choir rehearsal in Washington State earlier this month were diagnosed or are suspected of having COVID-19, the Los Angeles Times reported .
Three people have been hospitalized, and two have died. The event can be considered a "super spreading event" because of the high infection rate of those who attended.
"We think it was just a really super-unfortunate, high-risk occurrence," Polly Dubbel, the county health official, told the LA Times.
Robert Kim-Farley, a professor at UCLA Fielding School of Public Health, previously told Business Insider that a super spreading event is a situation that allows for a virus, like the novel coronavirus, to spread among people quickly.
Jamie Lloyd-Smith, a UCLA infectious disease researcher, told the LA Times it's likely that the forceful breathing from singing sent out the viral particles into the room, and people inhaled them.
"One could imagine that really trying to project your voice would also project more droplets and aerosols," he told the LA Times.
Kim-Farley explained that while some people may be "super spreaders," meaning they can transmit the virus more easily to more people, other times, events create a situation that allows for a virus to spread more easily.
A person can be a super spreader if they can emit large doses of a virus, that could be because they have a larger viral load, or even if they have mild symptoms and are unaware that they're sick, Kim-Farley explained.
"Some people are more efficient at transmitting the disease," Kim-Farley said.
Additionally, some people may be "super spreaders" based on circumstances such as being someone who is highly sociable or interacts with a significant number of people for work, especially if it is done in close proximity. They're able to expose a lot more people to a virus, Kim-Farley explained.
However, eight people who attended the rehearsal told the LA Times that no one appeared physically sick.
The choir event could be a super spreading event since people were singing near each other for a prolonged time.
While leaders at the Skagit Valley Chorale initially debated whether to have the weekly rehearsal on March 10, amid news of the virus spreading in the Seattle area because no cases were reported in the Mount Vernon area and schools and business were still open, the rehearsal continued.
"I'm planning on being there this Tuesday, March 10, and hoping many of you will be, too," Adam Burdick, the choir's conductor, wrote in an email to the 121 members of the choir.
Those who attended were given hand sanitizer and did not shake hands or hug as usual. However, the two and a half hours of singing may have helped spread the virus.
Some experts suggested that the event was evidence that the new coronavirus can be spread through aerosol particles, which can stay in the air for minutes or longer. However, the World Health Organization says the virus mainly spreads through larger droplets that don't stay in the air, the LA Times reported.
In one study, the New England Journal of Medicine showed that the virus could stay in the air and be infectious for three hours in a lab setting, it most likely would only remain in the air for 30 minutes in normal conditions.
But a study published March 17 in the New England Journal of Medicine found that when the virus was suspended in a mist under laboratory conditions, it remained "viable and infectious" for three hours though researchers have said that time would probably be no more than a half-hour in real-world situations, the LA Times added.
More than 163,000 people have been infected with the new coronavirus in the US, and over 3,000 have died.
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