This study tests a new medicine called concizumab for people with haemophilia A or B. Haemophilia is a condition where blood doesn't clot properly, leading to excessive bleeding. Some people with haemophilia also have inhibitors, which are substances that make standard treatments less effective. The study checks if concizumab can help prevent bleeding and is safe to use.

Participants will need to inject the medicine under the skin every day using a special pen. The study will last from 2 to 4 years, depending on when the medicine becomes available in stores in their country.

• The study requires daily self-injections over several years.
• Participants could be male children under 12, or anyone previously treated with concizumab.
• Those with certain health conditions, like clotting disorders, might not join.