The formation process of N-glycosylation and O-glycosylation in SARS-CoV-2. According to the complexity of the glycans, the N-glycosylation (a) is classified into oligomannose-type (2HexNAc), hybrid-type (3HexNAc), and complex-type (with more than 3HexNAc) glycans, whereas the mucin O-...