PF4 and Thrombocytopenia: Similarly, in a longitudinal study consisting of 71 VITT patients, Schönborn et al. [80] found that platelet-activating anti-PF4 antibodies became undetectable in 87% of patients over a mean of 79 weeks following initial symptom onset, with no further episodes of thrombosis or thrombocytopenia observed in 93% of patients, suggesting a generally low risk of VITT recurrence after the initial stage of symptom onset [80].