[Thrombosis and COVID-19 vaccine: much ado about nothing?].

Several cases of thrombosis in unusual sites associated with thrombocytopenia have been described after vaccination with the recombinant adenoviral vector encoding the spike protein antigen of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), ChAdOx1 nCov-19 (AstraZeneca) and Ad26.COV.2 (Johnson & Johnson/Janssen). This new clinical entity has many analogies with heparin-induced thrombocytopenia, and recent studies suggest that an immunologic mechanism may be implicated in the pathogenesis of this unusual thrombotic disorder. However, more data are needed to identify subjects at risk for this rare clotting disease.