strong anti-coronavirus activity.
•  Polysaccharide adjuvant can enhance the immunity and antiviral effect of vaccine.
•  Polysaccharides play important roles in antiviral nanomaterial and delivery system.
•  A new idea to develop COVID-19 vaccine combining polysaccharides and nanotechnology is proposed.

1  Introduction
The present outbreak of a coronavirus-associated acute respiratory disease called coronavirus disease 19 (COVID-19)