A Study to Evaluate the Real-world Usage and Effectiveness of Elocta and Alprolix in Patients With Haemophilia A or B

Inclusion Criteria: * Have a diagnosis of haemophilia A or B and previously treated with factor Product * Have started prophylactic Elocta/Alprolix treatment prior to enrollment visit, or at enrollment prescribed prophylactic treatment with Elocta or Alprolix regardless of participation in the study * Signed and dated informed consent provided by the patient, or the patient's legally acceptable representative for patients under the legal age, Before any study-related activities are undertaken. Assent should be obtained from paediatric patients according to local regulations. Exclusion Criteria: * Participation in an investigational medicinal product trial, from four weeks prior to first injection with Elocta or Alprolix to enrollment visit.