Administration of the COVID-19 vaccine has been associated with thrombosis and thrombocytopenia, a condition referred to as Vaccine-Induced Thrombotic Thrombocytopenia (VITT).
Associated vaccines: Johnson & Johnson, AstraZeneca (both use a replication-incompetent adenoviral vector)
Mechanism: antibodies against Platelet Factor 4 (PF4)
The patient presents with a thrombosis or embolism within a few weeks of receiving a COVID-19 vaccine, usually the first dose.
Sites of thrombosis have included:
(1) cavernous venous sinus
(2) mesenteric vein
(3) splanchnic vein
(4) portal vein
Laboratory findings:
(1) thrombocytopenia
(2) elevated D-dimer
(3) anti-PF4 antibodies
(4) reduced plasma fibrinogen
Management protocols have included high-dose IV immunoglobulin (IVIG) and anticoagulation with a non-heparin anticoagulant.
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