Prothrombotic Antibodies Targeting the Spike Protein's Receptor-Binding Domain in Severe COVID-19

Thromboembolic complication is common in severe coronavirus disease (COVID-19), leading to an investigation into the presence of prothrombotic antibodies akin to those found in heparin-induced thrombocytopenia (HIT). In a study of samples from 130 hospitalized patients collected 3.6 days after COVID-19 diagnosis, 80% had IgG antibodies recognizing complexes of heparin and platelet factor 4 (PF4/H), and 41% had antibodies inducing PF4-dependent P-selectin expression in CpG-treated …