Safety and Efficacy of Nonacog Beta Pegol (N9-GP) in Previously Untreated Patients With Haemophilia B

Inclusion Criteria: * Informed consent obtained before any trial-related activities. Trial-related activities are any procedures that are carried out as part of the trial, including activities to determine suitability for the trial * Male, age below 6 years at the time of signing informed consent * Patients with the diagnosis of haemophilia B (FIX (coagulation factor IX) activity level below or equal to 2%) based on medical records or central laboratory results * Previously untreated or exposed to FIX containing products less than or equal to 3 exposure days (5 previous exposures to blood components is acceptable) Exclusion Criteria: * Any history of FIX inhibitors (defined by medical records) * Known or suspected hypersensitivity to trial product or related products * Previous participation in this trial. Participation is defined as first dose administered of trial product * Receipt of any investigational medicinal product within 30 days before screening * Congenital or acquired coagulation disorder other than haemophilia B * Any chronic disorder or severe disease which, in the opinion of the Investigator, might jeopardise the patient's safety or compliance with the protocol * Patient's parent(s)/LAR(s) (legally acceptable representative) mental incapacity, unwillingness to cooperate, or a language barrier precluding adequate understanding and cooperation