Venous Thromboembolism and Mild Thrombocytopenia after ChAdOx1 nCoV-19 Vaccination
Nadia Gabarin, Sarah Patterson, Menaka Pai, Tamoor Afzaal, Ishac Nazy, Jo‐Ann I. Sheppard, Donald M. Arnold, Theodore E. Warkentin
Abstract
Thrombocytopenia and thrombosis have been reported following vaccination with the ChAdOx1 nCoV-19 (AstraZeneca) vaccine, an adenoviral vector COVID-19 (coronavirus disease 2019) vaccine.[1] [2] [3] [4] [5] Previous cases of vaccine-induced immune thrombotic thrombocytopenia (VITT) have been reported with symptom onset between 5 to 30 days postvaccination, typically with severe thrombocytopenia, unusual thromboses, high mortality, and platelet-activating antibodies against platelet factor 4 (PF4) despite no previous exposure to heparin.[1] [2] [3] Here we report two patients with VITT presenting as lower limb venous thrombosis (one with concurrent pulmonary embolism) and mild thrombocytopenia. One had a late presentation 31 days postvaccination. Both patients were shown to have platelet-activating antibodies in a PF4-dependent serotonin-release assay (SRA).