key: cord-0697388-kd7q4xqb
authors: Roberge, Guillaume; Carrier, Marc
title: Persistence of Platelets Activation Prior to Second Doses of Covid-19 Vaccine After Vaccine-Induced Immune Thrombotic Thrombocytopenia
date: 2022-03-11
journal: Clin Appl Thromb Hemost
DOI: 10.1177/10760296221086283
sha: a21dff9d904692ab2622a4953d872e0f1646988f
doc_id: 697388
cord_uid: kd7q4xqb

nan

A recent letter to the editor published in the New England Journal of Medicine reports the safety of administration of a second dose of Covid-19 vaccine in patients with vaccine-induced immune thrombotic thrombocytopenia (VITT) following ChAdOx1 nCoV-19. None of the 40 cases who received a second dose has developed complication regardless of the vaccine received. 1 However, it is unclear if these patients were anticoagulated at that time or if platelet-activation assays remained positive prior to vaccination. Most of VITT cases shows normalization of platelet activation after 12 weeks. 2 However, positive platelet-activation assay at 3 months of confirmed VITT with further related complications, suggesting higher thrombosis risk, have been previously described. 3 One patient with positive platelet-activation assay before getting a second dose of Covid-19 vaccine while still receiving anticoagulation has also been reported, but no adverse events occurred. 2 Although mRNA vaccines are not associated with VITT, the physiopathology is not fully understood and, hence, it is still unclear if a second dose of Covid-19 vaccine in patients with positive platelet-activation assay is safe. 4, 5 Furthermore, anticoagulation at that time could potentially mitigate the heightened risk of recurrent thrombosis. Clarification on these characteristics in the 40 described patients would help clinicians to discuss risks and benefits of a second dose of covid-19 vaccine for these patients.

All authors contributed to writing of the manuscript and approved the final version.

Informed consent for patient information to be published in this article was not obtained because the nature of the manuscript (letter to the editor/opinion letter about an already published article) does not require consent.

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

The author(s) received no financial support for the research, authorship, and/or publication of this article.

Guillaume Roberge https://orcid.org/0000-0001-9294-0662

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