Cerebral Venous Thrombosis after BNT162b2 mRNA SARS-CoV-2 vaccine

Not applicable.

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

The patients gave their consent to the publication of the data. Details that might disclose the identity of the subjects under study have been omitted.

LD.

The Pfizer/BioNTech vaccine contains mRNA particles that are translated into a spike protein, whose immune recognition leads to antibody production. 7 Before translation, mRNA may bind to pattern recognition receptors inducing pro-inflammatory cascades. 8 This immune response might, theoretically, contribute as a trigger for thromboembolic events. This mechanism is different from the AstraZeneca vaccine (ChAdOx1 nCoV-19, Vaxzevria®) and Janssen vaccine (Ad26.COV2.S), which use a viral vector. Up to 08/05, 70 cases of CVT with AstraZeneca's vaccine have been reported in EudraVigilance and 5 cases with Janssen's, most occurring in women aged under 60, up to 2 weeks post-vaccination. 3 , 5 , 9 These cases had thrombocytopenia and antiplatelet-PF4-antibodies, with a probable auto-immune mechanism leading to an atypical form of immune thrombocytopenia. 10 Although the exact pathophysiological mechanism for this type of thrombosis is still not clear, patients seem to benefit from immunomodulatory therapy (with intravenous immunoglobulin and high dose corticosteroids), and a proposed treatment mechanism with immunomodulation and non-heparin-anticoagulation has recently been published 11 . However, our cases did not exhibit thrombocytopenia nor antiplatelet antibodies. There was no clinical or laboratory worsening after the start of enoxaparin. Moreover, both had good clinical outcome, with no or minor neurological deficits, and had additional CVT risk factors: combined hormonal contraception and a likely malignant renal neoplasm. Thus, despite the temporal relation with vaccination, these cases do not seem to be pathophysiologically different from regular CVT. Continuous pharmacovigilance is necessary to monitor adverse events and clarify this association.

The authors declare no conflict of interest.

LD researched literature. RR, JM, DF, PRS, AP, GG, LF, VF, and MC were involved in the clinical care and management of the patients. LD, RR and MC acquired, analysed, and interpreted the data and drafted the manuscript. RR and MC provided supervision and a critical revision of the paper. LD wrote the first draft of the manuscript. All authors reviewed and edited the manuscript and approved the final version of the manuscript. Written consent for publication was obtained from the patients.