Acquired Hemophilia A following Pfizer-BioNTech SARS CoV-2 mRNA vaccine, successfully treated with prednisolone and rituximab

Introduction Acquired haemophilia A (AHA) is a rare bleeding disorder, characterised by the presence of autoantibodies to clotting factor VIII (FVIII). AHA can be idiopathic or occur in the context of malignancy, autoimmune disease, drugs, or pregnancy. Recently, cases of AHA following both COVID-19 infection and vaccination have been reported. Case report We report the case of a 95-year-old female who was immunised with the Pfizer-BioNTech SARS CoV-2 mRNA vaccine, with doses given three weeks apart. Spontaneous bruising over her extremities appeared one week after the initial dose, with hospital admission occurring three weeks after the second. Examination revealed a large haematoma on the dorsum of the right hand with resultant bleeding and widespread ecchymoses. Investigations confirmed a diagnosis of AHA. Management and outcome Initial management included high dose prednisolone, recombinant Factor VIII and tranexamic acid. There was no significant clinical improvement after three days, so intravenous rituximab 100 mg weekly for four weeks was commenced. The activated partial thromboplastin time (aPTT) normalised after two doses and Factor VIII level reached 0.68U/ml on day + 22. The patient was successfully discharged from hospital after 37 days. Discussion Four cases of AHA following administration of COVID mRNA vaccines (Pfizer and Moderna) have been documented. AHA should be a differential in patients presenting with bleeding following COVID-19 vaccination, in the presence of a normal platelet count. Rapid recognition, prompt initiation of immunosuppressive treatment and rigorous supportive cares are required to minimise morbidity and mortality.