(A) Purified platelets from healthy donors (n = 3) were incubated with or without spike protein, and Western blot analysis was performed using indicated antibody after IP for spike protein (IP lane). Density of IP lane was analyzed. (B) Purified platelets (n = 3) were pretreated with indicated antibody before incubation with spike protein; spike protein on platelets detected by Western blot. (C and D) Purified platelets were pretreated with anti-CD42b or isotype antibody before incubation by spike protein or S-pseudovirus; spike protein binding (n = 5) and the expressions of P selectin and CD40L (n = 4) on platelets were examined by flow cytometry. As anti-CD42b control, red controls were indicated as spike protein and isotype antibody; blue controls indicated as S-pseudovirus and isotype antibody. (E) Recombinant S-RBD was incubated with ACE-2 or CD42b, and their interaction was measured by co-IP. (F) Fixed platelets were incubated with S-RBD, and platelet-vWF complexes were detected by flow cytometry using recombinant vWF and ristocetin. Comparisons were made with paired Student’s t test, except in B, which was assessed by 1-way ANOVA with Dunnett’s multiple-comparison test. Mean with SD and P value are displayed. *P < 0.05; **P < 0.01; ***P < 0.001.