Long-term Study Evaluating Joint Health in People With Haemophilia A Receiving Real-world Prophylactic Treatment With Efanesoctocog Alfa

Who May Qualify: 1. Male or female patient with a diagnosis of haemophilia A. 2. Capable of giving signed willing to sign a consent form, which includes compliance with the requirements and restrictions listed in the willing to sign a consent form form (ICF) and in this protocol. 3. Prescribed with efanesoctocog alfa prophylactic treatment within 6 months prior to study enrolment or at the latest at the enrolment visit, in accordance with local regulations. 4. Must have received prophylactic treatment(s) with any haemophilia product(s) for at least 12 months prior to being prescribed with efanesoctocog alfa treatment. 5. Have documented pre-study treatment data on haemophilia prophylaxis prescriptions and on treated bleeding episodes from the 12-months prior to being prescribed efanesoctocog alfa treatment and until enrolment into this study. 6. Willing to adhere to the visit schedule and to undergo mandatory study assessment (HJHS, PROs). 7. Willingness and the ability of the patient or their legally designated representative to document all bleeding episodes, including any treatments for those episodes. 8. For HEAD-US subgroup: Accept to undergo annual ultrasound assessment on the index joints (ankles, elbows, knees). Who Should NOT Join This Trial: 1. Acquired haemophilia A and other blood clotting disorders than hereditary haemophilia A. 2. Any positive FVIII inhibitor result (defined as inhibitor titre ≥0.6 Bethesda unit \[BU\]/mL) from the medical records in connection to the switch to efanesoctocog alfa until the enrolment visit. 3. Enrolment in a concurrent clinical interventional study, or intake of an investigational medicinal product (IMP), including for haemophilia prophylaxis, within 3 months prior to enrolment in this study. 4. Patient not suitable for participation, whatever the reason, as judged by the Investigator, e.g., patient is not able or willing to perform the study assessments. Always talk to your doctor about whether this trial is right for you.