Vaccine-induced immune thrombotic thrombocytopenia (VITT): Update on diagnosis and management considering different resources

Abstract

Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a rare but severe immunological reaction to the non-replicable adenoviral vector-based COVID-19 vaccines. Extreme activation of platelets and the coagulation system leads to a high risk of death from venous or arterial thrombosis or secondary hemorrhage. Public and clinician awareness has reduced mortality of VITT by nearly 90%. The World Health Organization provided a guideline in July 2021 on diagnosis and management of VITT (also called thrombosis with thrombocytopenia syndrome, or TTS). Since July 2021, new, clinically relevant information has become available. This update has been summarized by the authors in an informal process with recommendations for low resource environments. We provide new available evidence on VITT to empower clinicians to recognize VITT early, then effectively diagnose and treat the disorder to reduce morbidity and mortality. We strongly encourage production of clear management pathways for primary care settings and hospital settings.

Keywords: AstraZeneca; SARS-CoV-2 vaccine; adenoviral vector-based vaccine; cerebral vein sinus thrombosis; platelets; vaccine-induced immune thrombotic thrombocytopenia.

FIGURE 1

May‐Grünwald stained blood smear analysis (A‐J, microscopic analysis) and platelet histograms (E,F) from two patients with reduced platelet counts (K) suggestive of vaccine‐induced immune thrombotic thrombocytopenia (VITT). Blood counts revealed thrombocytopenia in both patients. In routine blood smears aggregated (A‐D; dotted arrows, platelet aggregates) and enlarged platelets (C‐D, solid arrows; May‐Grünwald Giemsa stain; scale bar 50 μm) were readily detectable upon hospitalization. Increased platelet volume was confirmed by impedance measurement (E,F; PLT histograms; LD = lower discriminator, UD = upper discriminator). The patients received intravenous argatroban and 2g/kg immunoglobulin on days 3 and 4 (patient 1) or on day 1 and 2 (patient 2) post hospitalization. Within 6–9 days, the platelet changes observed upon hospitalization normalized (G‐K). Obtained from: Zimmermann S, Federbusch M, Isermann B, Kohli S. Vaccine induced thrombotic thrombocytopenia: insights from blood smear. Thromb Haemost. 2021 Oct 28. doi: 10.1055/a‐1681‐7286. Online ahead of print, used with permission of authors and editor.