Background: Scientists have strongly implied that aerosols could be the plausible cause of COVID-19 transmission; however, aerosol transmission remains controversial.
The study: We investigated the epidemiological relationship among infected cases on a recent cluster infection of COVID-19 in an apartment building in Seoul, South Korea. All infected cases were found along two vertical lines of the building, and each line was connected through a single air duct in the bathroom for natural ventilation. Our investigation found no other possible contact between the cases than the airborne infection through a single air duct in the bathroom. The virus from the first infected case can be spread to upstairs and downstairs through the air duct by the (reverse) stack effect, explaining the air movement in a vertical shaft.
Conclusions: This study suggests aerosol transmission, especially indoors with insufficient ventilation, which is underappreciated.
Keywords: SARS-CoV-2; South Korea; aerosol; bathroom; coronavirus; indoor; stack effect; ventilation.
Copyright © 2020. Published by Elsevier Ltd.