PF4 and Arterial thrombosis: The findings confirmed that: (1) the patients received ChAdOx1-S/nCoV-19 vaccine from 4 to 30 days before the event; (2) all the patients presented radiologic evidence of venous or arterial thrombosis; and (3) all were positive for PF4-heparin antibodies; (4) all had a reduced platelet count.