An epidemic caused by SARS-Coronavirus-2 (SARS-CoV-2) infection has appeared in Wuhan City in December 2019. The disease has shown a "clustering epidemic" pattern, and family-clustered onset has been the main characteristic. We collected data about 130 cases from 35 cluster-onset families (COFs) and 41 cases from 16 solitary-onset families (SOFs). The incidence of 2019 coronavirus disease (COVID-19) in COFs was significantly higher than that of SOFs. Our study also showed that patients with exposure to high-risk factors (respiratory droplets and close contact), advanced age, and comorbidities were more likely to develop COVID-19 in the COFs. In addition, advanced age and elevated neutrophil/lymphocyte ratio (NLR) were risk factors for death in patients with SARS-CoV-2 infection in the COFs.