Quarantine for discharged patients
After discharge from the hospital, patients were put under centralized quarantine and health monitoring for 14 days at designated health care facilities. During the quarantine period, the discharged patients lived in a well-ventilated single room, dined separately, practiced hand hygiene, and minimized close contacts. Nasopharyngeal and anal specimens collected on the 1st, 7th, and 14thdays or more frequently were sent to the laboratory for RT-PCR testing. The discharged patients were monitored for body temperature, and medical staff recorded whether they had respiratory symptoms (such as fever and dry cough) or digestive tract symptoms (such as diarrhea) every day. If the RT-PCR test result was consecutively negative and no symptoms or CT images progressed, these patients could return to normal life and be regularly followed up by the community after the discontinuation of quarantine. If they were symptomatic (had clinical manifestations and had a positive RT-PCR test result) or asymptomatic (had no clinical manifestations but had a positive RT-PCR test result) patients, diagnosis and treatment should be conducted strictly in accordance with Chinese clinical guidance for COVID-19(National_Health_Commission_of_China, 2020 ). When the positive retest patients met the hospital discharge criteria, they were quarantined for another 14 days.