Acquired hemophilia A following influenza vaccination: a case report and literature review

Acquired hemophilia A (AHA) is a rare bleeding disorder caused by the development of autoantibodies against coagulation factor VIII. It is idiopathic in approximately 50% of cases, but is also reported in association with malignancies, autoimmune diseases, pregnancy, and medications. We describe an 81-year-old man who developed AHA after receiving an influenza vaccination. The patient was treated with hemostatic therapy and immunosuppressive agents, achieving complete clinical and laboratory remission. Although extremely rare, influenza vaccination may trigger the development of AHA and should be considered in the differential diagnosis of newly diagnosed cases without other identifiable causes.