he possibility for incomplete inactivation of viruses or recovering virulence exists, resulting in significant safety concerns (Zhang et al., 2014). Also, these traditional vaccines may induce the antibody-dependent enhancement (ADE) effect, as in the case of SARS-CoV infection (Luo et al., 2018b). Similarly, some viral-vectored vaccines can elicit specific antibody and cellular immune responses with neutralizing activity and protection, but they might also induce anti-vector immunity or present pre