Vaccine-induced immune thrombotic thrombocytopenia following AstraZeneca (ChAdOx1 nCoV-19) vaccine: report of two cases

Vaccination with ChAdOx1 nCoV-19 can result in vaccine-induced immune thrombotic thrombocytopenia (VITT). This phenomenon mimics heparin-induced thrombocytopenia, yet it does not require heparin as a trigger. This case report highlights the potentially lifethreatening complication associated with ChAdOx1 nCov-19 vaccine, clinical presentation, diagnostic approach, and treatment. We report two cases of vaccine-induced immune thrombotic thrombocytopenia after receiving the first dose of the ChAdOx1 nCoV-19 vaccine. We attribute these thrombotic conditions to the vaccine due to the remarkable temporal relationship. The proposed mechanism of VITT is a production of antibodies against platelet factor-4 resulting in massive platelet activation. Healthcare providers should be aware of the possibility of such a fatal complication, and the vaccine recipients should be warned about the symptoms of VITT.