Indoor airborne spread of COVID-19 supported in new study

New research from the University of Georgia supports growing evidence for airborne transmission of the novel coronavirus (COVID-19) in enclosed spaces, as described in a new study published in JAMA Internal Medicine.

In the study, researchers were able to link a community outbreak of COVID-19 in China to a source patient who likely spread the virus to fellow bus riders through the bus's air conditioning system. The study calls into question the prevailing thought on how COVID-19 can spread.

The researchers worked with epidemiologists from two regional Centers for Disease Control and Prevention in China to trace infections following a large outdoor worship event in Zhejiang province. Some of the attendees took two buses to the event creating a unique natural experiment for the researchers.

Both buses had closed windows and air conditioning running, but one bus carried a patient infected with the virus and the other did not, the study said. Of the passengers who later got sick, many of them rode on the same bus as the source patient. Even though the two groups later mixed in with the larger crowd at the event, the number of new cases attributed to the event were much lower, suggesting that the bus was the major point of transmission. Further, some of the bus passengers who later showed symptoms of COVID-19, the authors said, were not sitting close to the infected passenger.

These findings highlight scenarios where COVID-19 could be spread through fine aerosol particles being circulated in an enclosed space, and as the weather turns colder, the researchers said they hope this work will persuade more people to wear face masks in public areas, particularly in indoor spaces.

“Understanding the transmission routes of COVID-19 is critical to contain the pandemic, so that effective prevention strategies can be developed targeting all potential transmission routes," said Ye Shen, PhD, lead author of the study and an associate professor of epidemiology and biostatistics at the University of Georgia College of Public Health, in a statement. “Our findings provide solid support for wearing face covering in enclosed environments with poor ventilation.”

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