PF4 and Venous thrombosis: identified nine patients, who had not been exposed to either heparin or SARS‐Cov‐2 vaccination, who presented with thrombocytopenia, thrombosis and again, negative HIPA but positive platelet activation in the presence of PF4 (PIPA) platelet activation assays (i.e. HIPA test performed in the presence of PF4 rather than heparin) (see Diagnosis of VITT and VITT‐like disorders).