A Study Evaluating Physical Activity and Joint Health in Severe Haemophilia A Patients ≥12 Years Treated Once Weekly With Efanesoctocog Alfa

Key Inclusion Criteria: * Previous treatment for haemophilia A with any marketed recombinant and/or plasma-derived FVIII for at least 150 EDs. * Having received prophylactic treatment with any marketed recombinant and/or plasma FVIII or emicizumab per local label for at least 12 months preceding enrolment. * Having 12 months documented pre-study treatment data regarding prophylactic treatment prescriptions and 6 months data on bleeding episodes prior to baseline visit. * Willingness and ability to complete training in the use of the study ePD and to use the ePD in their own smartphone throughout the study. * Willingness and ability to use the activity tracker provided by the sponsor to measure physical activity and heart rate. * Be able and willing to administer efanesoctocog alfa intravenously at home. Key Exclusion Criteria: * Serious musculoskeletal and/or neurological impairment limiting the mobility and the physical ability to a degree that makes the patient unsuitable for the study as judged by the investigator. * Other known coagulation disorder(s) in addition to haemophilia A. * History and/or current positive inhibitor test defined as ≥0.6 BU/mL. * Treatment with NSAIDs above the maximum dose specified in the prescribing information within 2 weeks prior to screening. * Systematic treatment within 12 weeks prior to screening with chemotherapy and/or other immunosuppressive drugs. * Treatment with an investigational product within 30 days or 5.5 half-lives prior to …