The primary objective of this study is to investigate weekly prophylaxis dosing regimens used in standard clinical practice.

In addition the study will capture reported bleed rate, pattern of change in KOVALTRY prophylaxis dose & dosing frequency, reason for choice of treatment regimen, FVIII product switch pattern, patient treatment satisfaction and adherence, KOVALTRY pharmacokinetic data (if performed), KOVALTRY consumption, as well as safety data.

Open label, prospective, non-interventional, single arm study in patients receiving KOVALTRY as prophylaxis therapy.

Inclusion Criteria:

• Male patients diagnosed with moderate to severe hemophilia A (≤ 5% FVIII:C (Factor VIII Coagulant activity))

• Any age

• ≥ 50 exposure days (EDs) to any FVIII product

• Patients with or without history of inhibitors

  • Patient with previous history of inhibitors, with at least 2 consecutive negative inhibitor tests and on standard prophylaxis therapy for at least 1 year prior to study entry

  • No current evidence of FVIII inhibitor or clinical suspicion of FVIII inhibitor

    • Evidence of FVIII inhibitor as measured by the Nijmegen-modified Bethesda assay [<0.6 Bethesda units (BU/mL)] or Bethesda assay [< 1.0 BU/mL] in 2 on consecutives samples
    • Documented or clinical suspicion of shortened FVIII half-life (< 6 hrs)

• Currently on or plan to start prophylaxis therapy with KOVALTRY

• Written informed consent

Exclusion Criteria:

• Patients participating in an investigational program with interventions outside of routine clinical practice
• Patients with an additional diagnosis of any bleeding/coagulation disorder other than hemophilia A
• Patients on Immune Tolerance Induction (ITI) treatment at the time of enrollment

Previously treated male patients with moderate to severe (≤ 5% FVIII:C) hemophilia A, with ≥ 50 exposure days (EDs) to any FVIII product and with or without history of inhibitors who have been prescribed KOVALTRY for a medically appropriate use will be eligible to be included into this study.