BACKGROUND:Since its discovery, SARS-CoV-2 has been spread throughout China before becoming a global pandemic. In Beijing, family clusters are the main mode of human-human transmission accounting for 57.6% of the total confirmed cases. METHOD:We present the epidemiological and clinical features of the clusters of three large and one small families. RESULT:Our results revealed that SARS-CoV-2 is transmitted quickly through contact with index case, and a total of 22/24 infections were observed. Among those infected, 20/22 had mild symptoms and only two had moderate to severe clinical manifestations. Children in the families generally showed milder symptoms. The incubation period varied from 2 to 13 days, and the shedding of virus from the upper respiratory tract lasted from 5 to over 30 days. A prolonged period of virus shedding (>30 days) in upper respiratory tract was observed in 6/24 cases. CONCLUSION:SARS-CoV-2 is transmitted quickly in the form of family clusters. While the infection rate is high within the cluster, the disease manifestations, latent period, and virus shedding period varied greatly. We therefore recommend rigorously testing contacts even during the no-symptom phase and consider whether viral shedding has ceased before stopping isolation measures for an individual.