Eight members of a big family with laboratory-confirmed COVID-19 pneumonia were admitted to First Hospital of Jilin University, Changchun, China, from 28 January to 5 February 2020 . The clinical records, laboratory results, and chest computed tomography (CT) scans were retrospectively reviewed . Throat swab samples were positive for severe acute respiratory syndrome coronavirus 2, confirmed by the Center for Disease Control and Prevention of Changchun . All eight patients had fever of different degrees; and 6 , 3, and 2 had cough; diarrhea; and sore throat . With disease progression, the percentage of lymphocytes in older patients increased, CT images worsened, and the ratio of lymphocytes increased when images revealed inflammation absorption . Although the CT images showed ground-glass opacities in the youngest patient, his lymphocyte count did not decrease with mild clinical symptoms, and the images showed that inflammation was quickly absorbed . Only the oldest patient developed critical illness . The C reaction protein (CRP) levels of Patient 5 increased significantly, and the rate of decline was the slowest, while his condition was the most severe . The clinical manifestations of COVID-19 in this family cluster varied with contact, age, and underlying disease . Lymphocyte count and quality of chest CT images appeared inversely associated with disease severity . CRP changes may be an indicator of disease severity and prognosis.