Treatment and detection of vaccine-induced thrombotic thrombocytopenia (VITT)

Quel est l’objet de cette étude?

Vaccination with an adenoviral vector vaccine against COVID-19 (i.e., ChAdOx1 nCoV-19, AstraZeneca) has been associated with a rare clotting disorder that has become known as vaccine-induced immune thrombotic thrombocytopenia (VITT). The clotting disorder develops when IgG antibodies recognize a platelet protein (PF4), forming a PF4-polyanion complex, which strongly activates platelets. This leads to a decrease in the number of platelets (platelet consumption) and promotes clot formation.  

Little is known about treating patients with VITT. The recommendation to use high-dose intravenous immune globulin (IVIG) to reduce platelet activation is based on the observation that VITT strongly mimics autoimmune heparin-induced thrombocytopenia (HIT) (even though patients with VITT usually have not received the anticoagulant heparin). For HIT, IVIG can be an important adjunct treatment. 

This report describes three Canadian patients who developed VITT after receiving the AstraZeneca vaccine. Using a newly developed diagnostic test for VITT, researchers documented the inhibition of platelet activation after treatment with IVIG in these three patients.