COVID-19 outbreak linked to fecal aerosol transmission in one study

Nine COVID-19-positive patients from three families in China lived in vertically aligned apartments in the same building connected by drainage pipes in the master bathrooms.

An outbreak of COVID-19 in an apartment building in China may have been caused by fecal aerosol transmission, according to a recent study.

Researchers studied an outbreak of COVID-19 in a high-rise apartment building in China to determine the temporal and spatial distributions of three infected families and look at associated environmental variables indicating a potential role of fecal aerosols. Locations of infected apartments and positive environmental samples and spread of virus-laden aerosols were measured. The study results were published Sept. 1 by Annals of Internal Medicine.

Nine patients in three families living in the same apartment block were infected with SARS-CoV-2. Of the three infected families, one had traveled to Wuhan, the epicenter of the COVID-19 pandemic. The other two families had no travel history and later symptom onset. The three infected families lived in vertically aligned apartments that were connected by drainage pipes in the master bathrooms. The locations of positive environmental samples and the observed infections were considered consistent with vertical spread of the virus via aerosols through stacks and vents. Throat swabs were also taken from 193 additional building residents and 24 members of the building management staff in the same apartment block, and all were negative. No evidence of transmission via the elevator or other locations was found.

The researchers noted that their evidence was circumstantial but concluded that the COVID-19 outbreak in this apartment building could have been caused by fecal aerosol transmission. Such transmission can be controlled at the source by avoiding potential gas leaks from the drainage system to indoor spaces and promoting adequate hygiene in sanitary drainage, they said. “Our study also indirectly suggests the importance of bathroom ventilation and hygiene, because toilet flushing may generate fecal aerosols,” the authors wrote. “Further studies are warranted to examine the role of fecal aerosols in the spread of SARS-CoV-2.”

An accompanying editorial said this and other evidence of SARS-CoV-2 transmission via wastewater isn't yet strong enough to merit wide-scale intervention but should prompt some precautions. The current study “add[s] to the growing body of evidence that wastewater plumbing systems, particularly those in high-rise buildings, deserve closer investigation, both immediately in the context of SARS-CoV-2 and in the long term, because they may be a reservoir for other harmful pathogens,” the editorialist wrote.