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Vaccine induced thrombotic thrombocytopenia: The shady chapter of a success story.
Tsilingiris, Dimitrios; Vallianou, Natalia G; Karampela, Irene; Dalamaga, Maria.
  • Tsilingiris D; First Department of Propaedeutic Internal Medicine, School of Medicine, National and Kapodistrian University of Athens, Laiko General Hospital, 17 St Thomas Street, 11527, Athens, Greece.
  • Vallianou NG; First Department of Internal Medicine, Evangelismos General Hospital, 45-47 Ipsilantou Str, 10676, Athens, Greece.
  • Karampela I; Second Department of Critical Care, Attikon General University Hospital, Medical School, National and Kapodistrian University of Athens, 1 Rimini St, Haidari, 12462, Athens, Greece.
  • Dalamaga M; Department of Biological Chemistry, School of Medicine, National and Kapodistrian University of Athens, 75 Mikras Asias, 11527 Athens, Greece.
Metabol Open ; 11: 100101, 2021 Sep.
Article in English | MEDLINE | ID: covidwho-1275587
ABSTRACT
The recognition of the rare but serious and potentially lethal complication of vaccine induced thrombotic thrombocytopenia (VITT) raised concerns regarding the safety of COVID-19 vaccines and led to the reconsideration of vaccination strategies in many countries. Following the description of VITT among recipients of adenoviral vector ChAdOx1 vaccine, a review of similar cases after Ad26.COV2·S vaccination gave rise to the question whether this entity may constitute a potential class effect of all adenoviral vector vaccines. Most cases are females, typically younger than 60 years who present shortly (range 5-30 days) following vaccination with thrombocytopenia and thrombotic manifestations, occasionally in multiple sites. Following initial incertitude, concrete recommendations to guide the diagnosis (clinical suspicion, initial laboratory screening, PF4-polyanion-antibody ELISA) and management of VITT (non-heparin anticoagulants, corticosteroids, intravenous immunoglobulin) have been issued. The mechanisms behind this rare syndrome are currently a subject of active research and include the following 1) production of PF4-polyanion autoantibodies; 2) adenoviral vector entry in megacaryocytes and subsequent expression of spike protein on platelet surface; 3) direct platelet and endothelial cell binding and activation by the adenoviral vector; 4) activation of endothelial and inflammatory cells by the PF4-polyanion autoantibodies; 5) the presence of an inflammatory co-signal; and 6) the abundance of circulating soluble spike protein variants following vaccination. Apart from the analysis of potential underlying mechanisms, this review aims to synopsize the clinical and epidemiologic features of VITT, to present the current evidence-based recommendations on diagnostic and therapeutic work-up of VITT and to discuss new dilemmas and perspectives that emerged after the description of this entity.
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Full text: Available Collection: International databases Database: MEDLINE Type of study: Diagnostic study / Prognostic study Topics: Vaccines / Variants Language: English Journal: Metabol Open Year: 2021 Document Type: Article Affiliation country: J.metop.2021.100101

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Full text: Available Collection: International databases Database: MEDLINE Type of study: Diagnostic study / Prognostic study Topics: Vaccines / Variants Language: English Journal: Metabol Open Year: 2021 Document Type: Article Affiliation country: J.metop.2021.100101