Marietta, Coluccio, and Luppi present a comprehensive review of the current understanding and hypotheses on the mechanisms of vaccine-induced immune thrombotic thrombocytopenia (VITT) [1]. Although the title of the review implicates a somewhat broader discussion, the authors focus on patients with VITT among the several entities leading to thrombocytopenia and/or thrombotic complications after the vaccination against coronavirus disease 2019 (COVID-19). The term VITT is restricted to cases in whom high titer anti-PF4 antibodies are present in the typical time window of 5–30 days after the COVID-19 vaccination, together with a reduced platelet count, high D-dimer levels and very often new thrombosis [2,3].
