Coronaviruses are enveloped nonsegmented positive-sense RNA viruses, which are broadly distributed in humans and other mammals, including camels, bats, masked palm civets, mice, dogs, and cats [1]. Although most human coronavirus infections are mild, coronaviruses have caused two large-scale pandemics in the last two decades: severe acute respiratory syndrome (SARS) with a mortality rate of 10%, and Middle East respiratory syndrome (MERS) with a mortality rate of 37%, together causing more than 10,000 cumulative cases [2, 3].

In December 2019, the Chinese city of Wuhan became the center of an outbreak of pneumonia of unknown cause [4]. Several patients with viral pneumonia were found to be epidemiologically associated with the Huanan seafood market in Wuhan, where a number of nonaquatic animals such as birds and rabbits were also on sale [5]. Bronchoalveolar lavage fluid (BALF), oral swabs, anal swabs, and blood samples from patients with severe pneumonia were investigated forpathogendiagnosisattheearlystageof the outbreak. Soon, a novel coronavirus was isolated from patients, and the SARS-CoV-2, previously named “2019 novel coronavirus”(2019-nCoV), was identified using next-generation sequencing [6].