• Must have completed the dosing planned in the primary pediatric ustekinumab study

• Benefit of continued ustekinumab therapy (that is, a clinical response or clinical remission as defined in the primary study at the final efficacy visit of the primary study)

• Parent(s) (preferably both if available or as per local requirements), legal guardian(s) or their legally acceptable representative must sign an informed consent form (ICF) indicating that he or she understands the purpose of, and procedures required for, the study and is willing to allow the child to participate in the study. Assent is also required of children capable of understanding the nature of the study (typically 7 years of age and older) as described in Informed Consent Process. An adolescent who signs the assent form will be given the opportunity to sign an adult ICF at a later visit when they reach the age of majority during the study to indicate that he or she understands the purpose of, and procedures required for, the study and is willing to participate in the study

• Must be willing and able to adhere to the lifestyle restrictions specified in this protocol

• Females of childbearing potential must have a negative urine pregnancy test at enrollment and prior to study intervention administration