Confirmed case: individual with nasopharyngeal swabs that were positive for SARS-CoV-2, using laboratory-based PCR

Symptomatic patients: patients with laboratory-confirmed COVID-19 with symptoms such as fever, cough, sore throat and sputum

Asymptomatic case: individual with a positive nucleic acid test result but without any relevant clinical symptoms in the preceding 14 d and during hospitalization

Close contact: (1) anyone who had been within approximately 6 feet (2 meters) of a person infected with SARS-CoV-2 for longer than 10 min and (2) those who had direct contact with the infectious secretions of a COVID-19 patient

The duration of shedding was calculated as the number of days from the first positive nasopharyngeal sample to the last positive sample based on RT–PCR testing. The last positive sample was followed by a negative RT–PCR result on two sequential tests.