Epidemiological history: (1) a history of travel or residence in Wuhan city and surrounding areas, or other communities where COVID-19 cases had been reported in the last 14 days before symptom onset; (2) a history of contact with SARS-CoV-2 infectious cases (with positive nucleic acid test); (3) a history of contacting with patients with fever or respiratory symptoms from Wuhan city and surrounding areas, or other communities where COVID-19 had been reported in the last 14 days before symptom onset; (4) a history of contacting with cluster of confirmed cases (≥ 2 cases with fever and/or respiratory symptoms occurred within 2 weeks in small areas, such as home, office, class of school, etc).