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Despite precautions coronavirus (COVID-19) has swept through a community choir in Washington State in the US.
Even before Washington State had announced social distancing rules, the choir members had agreed nobody would attend practice if they had even a hint of illness and they’d keep themselves well apart.
Then the choir’s conductor emailed singers that amid the “stress and strain of concerns about the virus,” practice would proceed as scheduled.
“I’m planning on being there this Tuesday March 10, and hoping many of you will be, too,” he wrote.
Of the 60 people who attended the practice, 45 have developed symptoms and 27 so far have tested positive for the virus.
Two choir members have died, three have been hospitalised and others have struggled to overcome the illness.
Eight people who were at the rehearsal say nobody there was coughing or sneezing or appeared ill.
They say 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.
The outbreak has stunned county health officials, who thought he virus was almost certainly transmitted through the air from one or more people without symptoms.
The communicable disease and environmental health manager at Skagit County Public Health, says the case was a disturbing example of how contagious coronavirus can be and how it can spread among groups even when no one is symptomatic.
“It’s really too high risk for people to gather close together,” she says.
Experts say the choir outbreak is consistent with evidence that the virus can be transmitted through tiny particles that can float in the air for minutes or longer.
The World Health Organization has downplayed the possibility of aerosol transmission, stressing the virus is spread through much larger “respiratory droplets,” which are emitted when an infected person coughs or sneezes and quickly fall to a surface.
However, a study published in the New England Journal of Medicine found when the virus was suspended in a mist under laboratory conditions it remained “viable and infectious” for three hours.
This study also refutes researchers’ assertions that the viable and infections time period would probably be no more than a half-hour in real-world conditions.
One of the study authors, who is an infectious disease researcher, says it’s possible that choir members’ forceful breathing action while singing dispersed viral particles, which were then inhaled.
“One could imagine that really trying to project your voice would also project more droplets and aerosols,” he says.
An environmental engineer who is an expert on airborne transmission of viruses, says some people are especially good at exhaling fine material, producing 1,000 times more than others.
He wants the public to take the choir’s infection rate “as a powerful warning” that people must be “really careful”.
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