Thrombosis and Thrombocytopenia after ChAdOx1 nCoV-19 Vaccination

We report findings in five patients who presented with venous thrombosis and thrombocytopenia 7 to 10 days after receiving the first dose of the ChAdOx1 nCoV-19 adenoviral vector vaccine against coronavirus disease 2019 (Covid-19). The patients were health care workers who were 32 to 54 years of age. All the patients had high levels of antibodies to platelet factor 4-polyanion complexes; however, they had had no previous exposure to heparin. Because the five cases occurred in a population of more than 130,000 vaccinated persons, we propose that they represent a rare vaccine-related variant of spontaneous heparin-induced thrombocytopenia that we refer to as vaccine-induced immune thrombotic thrombocytopenia. ChAdOx1 nCoV-19 and Immune Thrombotic Thrombocytopenia This report describes a very rare but life-threatening sequela of vaccination with ChAdOx1 nCoV-19. Within 10 days after a first injection, five health care workers presented with thrombocytopenia and thromboses, including cerebral venous sinus thrombosis with catastrophic outcome. The apparent cause is an anti-PF4 antibody capable of platelet activation; intravenous immune globulin may be therapeutic.

Automated summary

This study reports five cases of venous thrombosis and thrombocytopenia occurring 7 to 10 days after receiving the ChAdOx1 nCoV-19 vaccine, suggesting a rare vaccine-induced immune thrombotic thrombocytopenia. The condition, which can lead to catastrophic outcomes such as cerebral venous sinus thrombosis, may be treated with intravenous immune globulin.