Exposure to ChAdOx1 nCov‐19 (AstraZeneca) within 4–42 days of symptom onset Thrombocytopenia or falling platelet count AND elevated D‐dimer (> 5 times upper limit of normal) or reduced fibrinogen levels Thrombosis: any deep vein thrombosis, pulmonary embolism or arterial thrombosis; thrombosis in uncommon sites such as the cerebral venous sinus system or splanchnic vein is strongly suggestive Antibodies detected against platelet factor 4–polyanion complexes Functional assay indicating patient derived plasma or serum induction of prothrombotic phenotype in healthy donor platelets

* Further details available at https://www.thanz.org.au/documents/item/591. ⁷