Study setting
This study was conducted in Wuhan No. 7 Hospital, which was originally a comprehensive Grade 2A hospital and then became one of the first batch designated hospitals for COVID-19 in Hubei Province. The hospital started to treat patients with COVID-19 on January 22, 2020. It comprises general isolation wards, intensive care unit (ICU), fever clinic, clinical laboratory, office areas, and restrooms (Fig 1 ). All regions of the hospital were divided into 2 categories: (1) moderate- and high-risk regions, including the medical areas such as patient room, nurses’ station, buffer room for taking off personal protective equipment (PPE), and fever clinic, and (2) low-risk regions, including the living quarters such as the restrooms, office areas, and buffer room for taking on PPE.
Fig 1 Room layout of the general isolation ward 1 and the living quarters showing environmental and air sampling sites. Numbered labels correspond to environmental sampling sites. ① beepers; ② bed rails; ③ desktops;④ bedside tables;⑤ oxygen cylinder valve;⑥ medical equipment such as ventilator, monitors, and X-ray devices, etc;⑦ door handles;⑧ elevator buttons;⑨ keyboards;⑩ computer mouses;⑪ telephones; ⑫ water machine buttons; A refers to air samples. The medical area with moderate and high risk contains patient's room, nurses station, buffer room for taking off PPE, and elevator; the living quarters with low risk contains the rest rooms, office area, and buffer room for taking on PPE.