Thrombotic Thrombocytopenic Purpura After Ad6.COV2.S Vaccination.

Thrombotic thrombocytopenic purpura (TTP) is caused by the deficiency of ADAMTS13, a von Willebrand factor cleaving protease, which results in thrombotic microangiopathy. It is characterized by microangiopathic hemolytic anemia, thrombocytopenia, and microvascular thrombosis leading to organ damage. It has an extremely high mortality rate if left untreated, making early diagnosis and treatment of the utmost importance. We report a case of TTP that developed after vaccination with Ad26.COV2.S COVID vaccine. We present a case of a 50-year-old African American female who presented with dyspnea one week after receiving the first dose of Ad26.COV2.S vaccine. Initial labs showed anemia, thrombocytopenia, and markers of intravascular hemolysis. The suspicion for thrombotic thrombocytopenic syndromes (TTS), vaccine-induced thrombotic thrombocytopenia (VITT), TTP, and Immune thrombocytopenic purpura (ITP) was high based on the history and laboratory results. Computed tomography (CT) of the chest and ultrasound of bilateral lower extremities did not show any evidence of thrombosis. The absence of thrombosis in the presence of a high PLASMIC score increased the suspicion of TTP over the other differentials. Diagnosis of TTP was confirmed when the ADAMTS13 level was low with an elevated autoantibody inhibitor level. The patient underwent treatment with corticosteroids, plasmapheresis, and rituximab with improvement in symptoms and platelet count. TTP and VITT are the possible differential diagnosis for a patient presenting with anemia, thrombocytopenia, and signs of hemolysis after vaccination with Ad26.COV2.S. It is necessary to differentiate these two clinical entities as the management varies based on the diagnosis.