Three highly pathogenic human coronaviruses (CoVs) have been identified so far, including Middle East respiratory syndrome coronavirus (MERS-CoV), severe acute respiratory syndrome (SARS) coronavirus (SARS-CoV), and a 2019 novel coronavirus (2019-nCoV), as previously termed by the World Health Organization (WHO).1–3 Among them, SARS-CoV was first reported in Guangdong, China in 2002.4 SARS-CoV caused human-to-human transmission and resulted in the 2003 outbreak with about 10% case fatality rate (CFR),1 while MERS-CoV was reported in Saudi Arabia in June 2012.5 Even though with its limited human-to-human transmission, MERS-CoV showed a CFR of about 34.4%.2 The 2019-nCoV was first reported in Wuhan, China in December 2019 from patients with pneumonia,6 and it has exceeded both SARS-CoV and MERS-CoV in its rate of transmission among humans.7 2019-nCoV was renamed SARS-CoV-2 by Coronaviridae Study Group (CSG) of the International Committee on Taxonomy of Viruses (ICTV),8 while it was renamed HCoV-19, as a common virus name, by a group of virologists in China.9 The disease and the virus causing it were named Coronavirus Disease 2019 (COVID-19) and the virus responsible for COVID-19 or the COVID-19 virus, respectively, by WHO.3 As of March 5, 2020, a total of 95,333 confirmed cases of COVID-19 were reported, including 3,282 deaths, in China and at least 85 other countries and/or territories.7 Currently, the intermediate host of SARS-CoV-2 is still unknown, and no effective prophylactics or therapeutics are available. This calls for the immediate development of vaccines and antiviral drugs for prevention and treatment of COVID-19.