[Source investigation on a familiar cluster of coronavirus disease 2019 in Dandong city of Liaoning Province].

To Track the source of the infection through an investigation of a clustering of coronavirus disease 2019(COVID-19), and provide scientific basis and Strategy for the effective control of the aggregated epidemic situation of COVID-19. Field epidemiological method was used to survey the cases and related close contacts in a family clustering epidemic of COVID-19 in Dandong city of Liaoning Province. We obtained survey data for a descriptive analysis.Real time RT-PCR technique was used to detect 2019-nCoV nucleic acid in samples collected from cases and related close contacts combined with serum specific antibody detection. A total of 3 confirmed cases and 2 asymptomatic infection cases were discovered in the clustering epidemic, with 34 close contacts.Of eight close family contacts visiting from other province, one patient was on the same flight as the confirmed case, and her antibody IgG was positive. The family clustering was caused by past infection case who visited her friend through Wuhan from other provinces to local area.