Marine polysaccharides, such as carrageenan, PGS, chitosan, and their derivatives, show good inhibitory activity against various viruses, which provides a reference for their research on coronavirus. Iota-carrageenan containing lozenges show highly active against human rhinovirus (HRV), influenza virus A H1N1, and HCoV OC43 throughout the entire dissolution process, and are a promising therapy against viral infections of throat [67]. The cationically modified chitosan, N-(2-hydroxypropyl)-3-trimethylammonium chitosan chloride (HTCC), shows significant inhibition against the human coronavirus HCoV-229E, HCoV-OC43, HCoV-NL63, and HCoV-HKU1, and its hydrophobically modified derivative (HM-HTCC) is a potent inhibitor of the coronavirus HCoV-NL63, indicating that HTCC polymers based on chitosan are effective inhibitors of all low-pathogenic human coronaviruses [68]. Acute viral upper respiratory tract infection, also known as common cold, is mainly caused by respiratory viruses such as rhinovirus, coronavirus, influenza virus [[69], [70], [71]]. Clinical trials applying iota-carrageenan nasal spray have shown to reduce the duration of a virus-confirmed common cold. Carrageenan nasal spray shows significant antiviral efficacy in three virus subgroups, HRV, human coronavirus, and influenza A virus (IAV), and the highest effectiveness was observed in human corona virus-infected patients. The reduced duration of disease was 3 days (p < 0.01), and the number of relapses was three times less (p < 0.01) in carrageenan treated corona-virus -infected patients compared to control patients [70].