Objective To retrospectively analyze COVID-19 case clusters of one imported COVID-19 case to provide a reference for the prevention and control of COVID-19. Methods COVID-19 case clusters of one imported COVID-19 case in a district of Chengdu city from January 2020 were selected. The epidemiological data were retrospectively analyzed to investigate source of infection and the transmission channels. Results A total of 5 confirmed COVID-19 cases showed clustering and all of them had a history of exposure to Hubei province. The distribution of onset time was January 25 in 3 cases

January 26 in 1 case

and February 2 in 1 case

with 2 cases presenting fever and 3 cases presenting cough. All the patients（5 cases） had normal lymphocyte counts and 1 patient had decreased total white blood cell counts; with the age ranging from 31 to 59 and a median age of 33. The median time from admission to discharge was 41 days in 5 patients

during which 2 patients tested positive for COVID-19 after recovery

and the median time from onset to the lifting of quarantine was 82 days. Conclusion Fever and cough were the initial symptoms of the COVID-19 case clusters

and lung CT showed different degrees of inflammation

suggesting that the initial symptoms of COVID-19 were not always fever. This COVID-19 case cluster further verities the great significance of regular epidemic surveillance and proves the importance of strengthening symptom surveillance in hospitals and quarantine facilities in epidemic prevention and control

and early detection

diagnosis

reporting

quarantine

and treatment should be observed.