Researchers Continue to Zero in on How COVID-19 Spreads

Talking and singing appear to spread COVID-19 far more effectively than simply breathing, according to a new study whose authors include current and future University of Maryland researchers. 

SARS-CoV-2 (the virus that causes COVID-19) is known to spread through the air, but researchers have been working to pinpoint how much virus hangs in small airborne particles. The new study published in Clinical Infectious Diseases last week found that 94% of the virus measured in the experiment was emitted while participants used their voices. 

Led by Kristen Coleman, a senior research fellow at Duke-NUS Medical School in Singapore who is joining the University of Maryland School of Public Health faculty this fall, the research also found the participants emitted 85% of virus particles through fine aerosols smaller than 5 micrometers, which float or drift around in the air and can be easily inhaled by others—especially in indoor settings.

“Our study demonstrates that tiny aerosols produced by breathing, talking, and singing contain the virus and therefore may play a critical role in the spread of COVID-19. This reinforces the importance of well-fitted masks, ventilation and air filtration to protect people from COVID-19,” Coleman said. “Schools especially should consider these data as they plan to reopen in person soon since many schools do not have adequate airborne virus protections in place.”

The study utilized the “Gesundheit II machine” developed by Don Milton, a professor of applied environmental health and co-author, to measure the “viral load” in respiratory aerosols emitted by COVID-19 patients during 30 minutes of breathing, 15 minutes of talking and 15 minutes of singing. 

The laboratory experiments conducted in the NUS Biosafety Level 3 Laboratory in Singapore revealed that 59% of participants emitted detectable levels of coronavirus in their breath, including three who were asymptomatic and one who would later develop symptoms. 

Singing emitted the highest amount of the virus overall, followed by talking, then breathing. Patients earlier in their illness were more likely to emit detectable levels of the virus, supporting a growing body of research that suggests that COVID-19 patients are more contagious in the early stages of their illness.

To further explore how COVID-19 and other respiratory diseases such as influenza are transmitted through the air, Coleman will be joining Milton’s Public Health Aerobiology, Virology and Exhaled Biomarker (PHAB) Laboratory as an assistant research professor this fall.