1. Patients with respiratory tract symptoms or fever, or asymptomatic and contact with confirmed COVID-19 at outpatients clinic 2. Performed nasopharyngeal swab for PCR-COVID on the enrollment date 3. Available for telephone interview 4. Able to sign written informed consent

1. Patients with respiratory tract symptoms or fever, or asymptomatic and contact with confirmed COVID-19 at outpatients clinic 2. Performed nasopharyngeal swab for PCR-COVID on the enrollment date 3. Available for telephone interview 4. Able to sign written informed consent