 The mean serial interval for confirmed cases of coronavirus disease in China from February 8, 2020 was estimated to be 3.96 days, 95% CI 3.53 to 4.39, with a standard deviation of 4.75 days, 95% CI 4.46 to 5.07, and 12.6% of case reports indicated pre-symptomatic transmission. This article was authored by Zhang Weidu, Xiaokasu, Yiwu, and others.