Introduction: Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a life-threatening prothrombotic disorder first identified following the introduction of adenoviral vector vaccines for COVID-19. The condition is characterized by anti-PF4 antibodies and clinically presents with thrombocytopenia and thrombosis often in unusual anatomical sites.
Areas covered: In this review, we discuss the clinical presentation, diagnostic testing, and treatment of VITT. We also review VITT-like syndromes that have been described in patients without previous vaccination. We propose a conceptual framework for the mechanism of anti-PF4 diseases that includes sufficiently high levels of PF4, the presence of a Polyanion that can form immune complexes with PF4, a Pro-inflammatory milieu, and an immunological Predisposition - the 4Ps.
Expert opinion: Significant progress has been made in understanding the characteristics of the VITT antibody and in testing methods that can confirm that diagnosis. Future work should be directed at understanding long-term outcomes, mechanisms of thrombosis, and individual risk factors for this rare but dangerous immune-thrombotic disease.
Keywords: VITT; VITT treatment; VITT-like syndromes; anti-PF4 antibodies; anti-PF4 antibody assays; long VITT; platelet activation assays.