A recent peer-reviewed study revealed one of the quickest and easiest ways to spread COVID-19: singing indoors, without a mask on.
The study, published in Indoor Air, confirmed what was already suspected after a choir rehearsal in early March became one of the first superspreading events in the US.
On March 10 in Skagit Valley, Washington, 61 people attended their regular 2.5-hour choir practice. One choir member admitted to showing flu-like symptoms prior to attending the rehearsal that evening. In the following weeks, 53 people who attended the rehearsal fell ill and tested positive for COVID-19. Of those, three people were hospitalized and two died.
Even though the attendees were careful not to touch each other and sanitize their hands, most of them still got sick. This was believed to be caused by the transmission and buildup of aerosols, which can increase through acts of talking loudly or singing, especially indoors. The recent study, led by professor of mechanical engineering Shelly Miller, verifies that.
“This study documents in great detail that the only plausible explanation for this superspreading event was transmission by aerosols,” Miller said. “Shared air is important because you can be inhaling what someone else exhaled even if they are far away from you.”
According to the researchers, there is not enough reason to believe that droplets and infected surfaces were responsible for transmitting the virus. For so many people to be infected in a short span of time, the virus must have been airborne somehow.
“The inhalation of infectious respiratory aerosol from ‘shared air’ was the leading mode of transmission,” study co-author Jose-Luis Jimenez said.
Additional research already speculated on the likelihood of COVID-19 transmission via aerosols. According to Miller, singing is known to produce high amounts of aerosols — more than whispering or talking at a normal volume.
“You have the air that’s coming out on your respiratory tube, your mouth, and your nose, and there’s some liquid that’s lining all of your respiratory system,” Jimenez explained. “And when the air is going very quickly, it can basically grab a little bit of that material and put it in a particle, and then you expel it out into the air. That’s what happens. So anything that makes the air go faster or more strongly or produce more air is putting out more respiratory particles. If you’re singing, you’re breathing in a lot of air, you’re breathing out very forcefully, and you’re also moving your vocal cords. The vocal cords are wet, they’re covered in this fluid, they’re vibrating, and that can also produce more particles.”
Not only this, but the likelihood of virus transmission only increases in an indoor setting, where the aerosol particles are trapped, making it almost impossible not to breathe in the virus.
Researchers noted that a 30-minute rehearsal, rather than a 2.5-hour one would have reduced the rate of infection from 87% to 12%.
For now, the study authors are recommending that choral directors move their rehearsals outdoors, if possible, as well as requiring all those attending to wear masks and stand 6 feets apart. However, the safest option would be to avoid singing in groups at all for a while, especially if getting outside isn’t an option for you.
“What we’re recommending right now is definitely staying six feet apart with masks, with good ventilation, in very short duration of 30 minutes, with breaks to air out the room,” Miller said.
The Center for Disease Control and Prevention (CDC) supported this conclusion and originally issued a report stating that group singing events were considered high-risk and increased chances of transmission. However, that language was later removed from CDC guidelines, due to political concerns.
However, experts say that the virus still needs to be taken seriously, and the recent findings in this study support that.
“[Group singing remains] extremely dangerous and irresponsible,” Jimenez said. “The research adds to the overwhelming body of evidence that aerosol transmission is playing a major role in driving this pandemic and especially to superspreading events.”
Dr. James Hamblin offered The Atlantic this simple advice to be considerate of others:
“A general rule for minimizing the spread of any respiratory virus: Silence is safer than whispering. Whispering is safer than talking. Talking is safer than singing.”