Antiplatelet antibody screening of VITT and thrombocytopenia patients after ChAdOx1 nCov-19 administration. A total of n = 53 patients with thrombocytopenia after ChAdOx1 nCov-19 vaccination were screened for antiplatelet antibodies. N = 27 of these patients had positive anti–PF4-heparin antibody tests, fulfilling the criteria for VITT. N = 26 patients had isolated thrombocytopenia. Of these groups, n = 8 and n = 11 patients had antiplatelet antibodies present in the serum, respectively. The mean platelet counts between positive and negative antiplatelet antibody cohorts did not differ significantly (Welch’s t test).