Three recently published papers2–4 reported case series of unusual and mostly devastating thrombosis, in particular cerebral venous thrombosis, associated with thrombocytopenia and a high level of antibodies against platelet factor 4 (PF4)-heparin, developing between 5 and 15 days from the first dose of ChAdOx1 nCoV-19 vaccine. This evidence concerns the gene PF4 and Thrombocytopenia.