 Abstract coronavirus disease 2019, COVID-19, caused by severe acute respiratory syndrome coronavirus 2, SARS-CoV-2, is an ongoing global health emergency. Here we highlight nine most important research questions concerning virus transmission, asymptomatic and pre-symptomatic virus shedding, diagnosis, treatment, vaccine development, origin of virus and viral pathogenesis. This article was authored by Kit Sen Yuan, Xi, Wei Yi, Xin Yi Feng, and others.