Vaccine-Induced Immune Thrombotic Thrombocytopenia Two Years Later: Should It Still Be on the Scientific Agenda?

Abstract

Vaccine-induced immune thrombotic thrombocytopenia (VITT) was recognized around 2 years ago, at the beginning of the anti-SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) vaccination campaign, as a rare but life-threatening complication of adenoviral vector vaccines. Two years later, the coronavirus disease 2019 (COVID-19) pandemic has been tamed, although not defeated, and the vaccines provoking VITT have been abandoned in most high-income countries, thus why should we still speak about VITT? Because a significant fraction of the world population has not been vaccinated yet, especially in low/middle-income countries that can only afford adenoviral vector-based vaccines, because the adenoviral vector platform is being used for the development of a large series of new vaccines for other transmissible diseases, and lastly because there are some clues suggesting that VITT may not be exclusive to anti-SARS-CoV-2 vaccines. Therefore, a deep understanding of this new syndrome is highly warranted as well as the awareness that we still miss some crucial insight into its pathophysiology and on some aspects of its management. This snapshot review aims to portray our knowledge on VITT, focusing on its clinical presentation, pathophysiological insight, diagnostic and management strategies, and to pinpoint the main unmet needs, highlighting the aspects on which research should focus in the near future.