Although a variety of vaccines have been developed against SARS-CoV and MERS-CoV, most of them are in the preclinical studies, and only several have been tested in clinical trials4 ,5 (Du et al., 2016b; Cho et al., 2018). Nevertheless, no vaccines have been approved for the prevention of SARS and MERS in humans, demonstrating the need to develop effective and safe vaccines to control current MERS-CoV infection, or to be stockpiled for potential use against re-emerged SARS-CoV or SARSr-CoV. Particularly, effective and safe vaccines are urgently needed to prevent and control the current outbreak of 2019-nCoV.