Adjunct Immune Globulin for Vaccine-Induced Immune Thrombotic Thrombocytopenia

This brief report outlines the clinical and laboratory responses to high-dose intravenous immune globulin (IVIG) in three Canadian patients diagnosed with vaccine-induced immune thrombotic thrombocytopenia (VITT) following ChAdOx1 nCoV-19 vaccination. All patients exhibited thrombosis in arterial or venous sites, severe thrombocytopenia, and high D-dimer levels. IVIG administration led to marked improvements in platelet counts and reduced ex vivo platelet activation, although ELISA testing showed continued antibody binding to PF4. Modified serotonin-release assays revealed variability in platelet reactivity profiles, with PF4-enhanced activation prominent in two patients. The report underscores IVIG’s inhibitory effects on VITT-related platelet activation and supports its early use alongside non-heparin anticoagulation.

This brief report outlines the clinical and laboratory responses to high-dose intravenous immune globulin (IVIG) in three Canadian patients diagnosed with vaccine-induced immune thrombotic thrombocytopenia (VITT) following ChAdOx1 nCoV-19 vaccination. All patients exhibited thrombosis in arterial or venous sites, severe thrombocytopenia, and high D-dimer levels. IVIG administration led to marked improvements in platelet counts and reduced ex vivo platelet activation, although ELISA testing showed continued antibody binding to PF4. Modified serotonin-release assays revealed variability in platelet reactivity profiles, with PF4-enhanced activation prominent in two patients. The report underscores IVIG’s inhibitory effects on VITT-related platelet activation and supports its early use alongside non-heparin anticoagulation.