Fig. 2

Comparison of RBD–ACE2 binding inhibition of serum samples between the severe and non-severe group. a The blocking percentage of serum to inhibit RBD-ACE2 interaction were showed. Serum was diluted at a final dilution of 1:40. The blocking percentages were calculated as 100 × (1 − (OD₄₅₀ value of serum sample/OD₄₅₀ value of PBS control)). b Pie charts showing the proportions of samples with positive (Red) or negative (Blue) RBD-ACE2-binding inhibition. Mann–Whitney U test was used to compare differences between the two groups