In December 2019, a novel coronavirus, which is now designated as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was first identified as the etiology of pneumonia of unknown cause in patients from Wuhan of central China. Since the first report of coronavirus disease 2019 (COVID-19), the disease became pandemic causing the large-scale outbreak all over the world. In this review, we discuss the clinical and epidemiological characteristics of COVID-19 in the early stage of outbreak based on recent reports from China. (Korean J Med 2020;95:67-73)