The antiviral mechanism of polysaccharides is usually related to its specific structure and virus type. Coronaviruses are enveloped positive-stranded RNA viruses that replicate in the cytoplasm [81]. To deliver the nucleocapsid into host cell, the coronavirus-cell entry procedure involves the fusion of the envelope with the host cell membrane mediated by viral S proteins (Fig. 2) [7,81], which is the main determinant of virus entry.