Results of the 9 patients with VITT-like features (Tables 1 and 2 ) with thrombocytopenia and thrombosis without proximate exposure to heparin or vaccination. Results of the rapid anti-PF4/heparin assay are given on the x-axis (cutoff: dashed vertical line). Results of new rapid anti-PF4 assay are given on the y-axis (cutoff: dashed horizontal line). Patient samples shown in green (patients 4, 7, and 8) were positive both in the PF4-dependent functional assay and a heparin-dependent functional assay, whereas patient samples in orange (patients 1, 2, 3, 5, and 6∗) exclusively tested positive in the PF4-dependent functional assay. Detail courses of patients 1,²⁰ 2,²¹ and 8²² were previously described. ∗Some samples of patient 6 from previous time points were weakly positive in the heparin-dependent functional assay and strongly positive in the PF4-dependent functional assay. Treatment of this patient after the time covered by this report is summarized in Lindhoff-Last et al.²³