Superspreader: Singing Indoors Unmasked Can Quickly Spread Covid-19
Fri, September 30, 2022

Superspreader: Singing Indoors Unmasked Can Quickly Spread Covid-19


Singing brings joy to many people and can be an excellent form of exercise. The lungs get a workout as the singer employs proper vocal projections and singing techniques. Other health benefits include strengthening the immune system (amount of proteins that function as antibodies increases), stimulated overall circulation, a stronger diaphragm, and boosts endorphins into the system that makes a person feel uplifted and energized. However, during the 2020 pandemic, singing indoors unmasked can quickly spread Covid-19 through aerosols or the microscopic airborne particles. This was confirmed in a new study conducted by researchers from the University of Colorado at Boulder.

Shared air, ventilation, and coronavirus

Shelly L.Miller, a professor of mechanical engineering, and colleagues document that the only plausible explanation for a superspreading event was the transmission of aerosols. She said that shared air is important because one person can be inhaling what someone else has exhaled even if they are far away from each other. Yet, poor ventilation in the indoor space can also lead to the build-up of aerosols. Inhaling the infectious respiratory aerosol from shared air is found to be the leading mode of Covid-19 transmission.

A superspreader at choir practice

The study cited the Covid-19 case in Skagit Valley, Washington, where one person with mild symptoms of Covid-19 attended a choir practice indoors that lasted for 2.5 hours. The event was attended by 61 persons, including the symptomatic index patient. In the weeks that followed, secondary Covid-19 cases happened with more than 50 people contracted the disease and two died. These people have attended the rehearsal and the CDC mentioned that the transmission was likely facilitated by the close proximity during the practice and augmented by singing.

The research team interviewed the choral through a representative. They found that the choir had taken precautions to avoid touching each other and they also sanitized. In short, the chorale members were serious about their health and music that day. What can’t be avoided, though, was that they touched few shared surfaces and shared the same restroom. However, many who did not use the restroom still got sick after attending the practice. What the research team found out was that these people did not wear face masks.



As narrated by Medical Xpress, there were simply not enough chances for infected surfaces (fomites) and droplets to transmit the coronavirus to the people who fell ill after attending the said practice. The research team believes the indoor space and poor ventilation led to the buildup of aerosols that were produced by singers. Not to mention the heat produced by the chorale members themselves was mixed in the indoor air. The rehearsal also lasted for 2.5 hours and there were many singers present. Hence, the shared air became the leading mode of transmission.

CDC said that the attack rate of such a superspreading event was 53.3% to 86.7%. For the present study, the authors said that reducing the rehearsal time to 30 minutes instead of 2.5 hours could have dropped the rate of infection to 12%. Improving ventilation, wearing face masks, rehearsing for half the duration, and using portable air cleaners could have dropped the number of infected chorale members from 52 to 5. This was based on an analysis conducted by co-author Jose-Luis Jimenez, a professor of chemistry and a fellow at the Cooperative Institute for Research in Environmental Sciences (CIRES), and team.



Such a superspreading event occurred in March when public health officials were just starting to debate whether face masks were necessary or not and businesses were just beginning to close in the US. The floating pieces of bodily fluids or aerosols were not believed to carry the Covid-19, said the CDC and WHO at that time. They only highlight to stand six feet apart and wash hands. However, after hearing the superspreading event in Washington State, Miller was not convinced. She added that the act of singing is known to release high amounts of bodily fluids, much smaller than droplets.

Since that month, other choir superspreading events happened in Canada, Austria, the Netherlands, France, Spain, England, Germany, and South Korea. Miller and the team’s study provide new insight into how the outbreaks happened and what the public can do in the future so that choral rehearsals will be safer.

Choral practices outdoors

The authors suggest a solution: conduct choral practices outdoors, if possible, during the pandemic. If there will be indoor singing events in the future, it is best to carefully manage it because singing can generate large amounts of infected aerosol if one of the singers is infected. Air cleaning, removing virus-containing aerosols from the air, and improved ventilation by drawing in more outdoor air can also help reduce the spread of the virus.

It also remains important for singers to wear masks and maintain the distance of at least 6-feet apart. The research team has submitted their findings in June yet the topic about aerosols remained not being openly acknowledged by the CDC and WHO as an important route for Covid-19 transmission.

Musicians, singers, & related workers

According to Data USA, musicians, singers, and related workers are most often hired by the religious organizations' industry. In 2016, their average yearly wage was $33,265. They are part of the arts, design, sports, media, and entertainment occupations. In terms of gender composition, about 60.4% of musicians, singers, and related workers are male.

As of May 2018, the US Bureau of Labor Statistics estimates that there were about 41,680 people employed as musicians or singers that may perform on stage, for on-air broadcasting, or video or sound recording. States with the highest employment level in this occupation include New York (0.83 employment per thousand jobs), California (0.36), Tennessee (0.77), Texas (0.14), and Florida (0.19).



Since we want to contain Covid-19, we have to find ways to protect people and make workplaces and environments less favorable for superspreading. As of September 22, the United States has 7,046,216 Covid-19 cases with 4,299,525 patients who have recovered, according to Worldometers.

With so much evidence about the risk factors associated with superspreading events, it makes sense for now to practice choral performance groups in a virtual setting.