Several different residents living in different households in the same apartment complex became infected with coronavirus and officials believe it may be because they all share the same ventilation system.
A cluster of cases was investigated in South Korea after a series of new patients were identified on various floors of a residential complex in Seoul.
On August 23, a woman living on the sixth floor tested positive, followed later by her husband and daughter.
The very next day, a child living one unit below the woman also tested positive for the virus. It was only when another woman living on the fourth floor was diagnosed with COVID-19 that health officials decided to test all 437 residents.
The mother of the infected child on the fifth floor tested positive as well as two more residents living several floors directly above them.
Two other cases were also reported in other units of the same building. These units were not aligned with the others but do share the same ventilation system.
“Each line was connected through a single air duct in the bathroom for natural ventilation,” investigators wrote.
They noted that all of the patients in separate units were not acquaintances and had no history of interpersonal contact.
“Our investigation found no other possible contact between the cases than the airborne infection through a single air duct in the bathroom.”
These findings suggest to researchers of the virus that people may need to stay indoors and away from others even more to avoid interpersonal contact but “some may be exposed to viral infection by inhalation due to inadequate ventilation systems.”
