Longitudinal Aspects of VITT.
Semin Hematol
; 59(2): 108-114, 2022 04.
Article
in English
| MEDLINE | ID: covidwho-1778659
ABSTRACT
In hundreds of patients worldwide, vaccination against COVID-19 with adenovirus vector vaccines (ChAdOx1 nCoV-19; Ad26.COV2.S) triggered platelet-activating anti-platelet factor 4 (PF4) antibodies inducing vaccine-induced immune thrombotic thrombocytopenia (VITT). In most VITT patients, platelet-activating anti-PF4-antibodies are transient and the disorder is discrete and non-recurring. However, in some patients platelet-activating antibodies persist, associated with recurrent thrombocytopenia and sometimes with relapse of thrombosis despite therapeutic-dose anticoagulation. Anti-PF4 IgG antibodies measured by enzyme-immunoassay (EIA) are usually detectable for longer than platelet-activating antibodies in functional assays, but duration of detectability is highly assay-dependent. As more than 1 vaccination dose against COVID-19 is required to achieve sufficient protection, at least 69 VITT patients have undergone subsequent vaccination with an mRNA vaccine, with no relevant subsequent increase in anti-PF4 antibody titers, thrombocytopenia, or thrombotic complications. Also, re-exposure to adenoviral vector-based vaccines in 5 VITT patients was not associated with adverse reactions. Although data are limited, vaccination against influenza also appears to be safe. SARS-CoV-2 infection reported in 1 patient with preceding VITT did not influence anti-PF4 antibody levels. We discuss how these temporal characteristics of VITT provide insights into pathogenesis.
Keywords
Full text:
Available
Collection:
International databases
Database:
MEDLINE
Main subject:
Thrombosis
/
Purpura, Thrombocytopenic, Idiopathic
/
COVID-19
Type of study:
Prognostic study
Topics:
Long Covid
/
Vaccines
Limits:
Humans
Language:
English
Journal:
Semin Hematol
Year:
2022
Document Type:
Article
Affiliation country:
J.seminhematol.2022.03.001
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