The CDC released a report on Tuesday documenting how an outbreak of COVID-19 in Washington state originated.
The data indicates that one choir singer was likely a “superemitter,” causing dozens of others to become ill.
According to the CDC, 53 members of a Skagit County, Washington, church choir who participated in a March 10 practice had a confirmed or probably case of the coronavirus.
On March 10, 61 members of the 122-member church choir attended a 2.5-hour choir practice. One of the participants sang despite having coronavirus symptoms at the time, the CDC said.
A week after the practice, a member of the choir called the Skagit County health department to inform them several members of the choir had become ill. By March 17, 24 people had reported having symptoms of the virus.
The choir had a practice on March 3. Of those who attended the March 3 practice but not the March 10 practice, only one of the 21 singers had a coronavirus case.
Through contact tracing, the CDC found that three singers were hospitalized with two of them dying from coronavirus-related illnesses. The CDC said that nearly 90% of those with a case of the virus had a cough, 68% had a fever, 65% had myalgia and 60% had a headache.
“The act of singing, itself, might have contributed to transmission through emission of aerosols, which is affected by loudness of vocalization,” the CDC said.
The CDC said the proximity of singers contributed to the rapid spread of the virus.
“Aerosol emission during speech has been correlated with loudness of vocalization, and certain persons, who release an order of magnitude more particles than their peers, have been referred to as superemitters and have been hypothesized to contribute to superspeading events,” the CDC said. “Members had an intense and prolonged exposure, singing while sitting 6–10 inches from one another, possibly emitting aerosols.”
To read the full CDC report, click here.