A Long-term Extension Study of Ustekinumab in Pediatric Participants

Inclusion Criteria: * 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 Exclusion Criteria: * Are pregnant, nursing, or planning pregnancy or fathering a child * Have had any of (a) confirmed severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2 \[COVID-19\]) infection (test positive), or (b) suspected SARS-CoV-2 infection (clinical features without documented test results), or (c) close contact with a person with known or suspected SARS-CoV-2 infection: Exception: (i) may be included with a documented negative result for a validated SARS-CoV-2 test: obtained at least 2 weeks after conditions (a), (b), (c) above (timed from resolution of key clinical features if present, example, fever, cough, dyspnea) and (ii) with absence of all conditions (a), (b), (c) above during the period between the negative test result and the baseline study visit * Taken any disallowed therapies as noted in the primary study, before the planned first long-term extension (LTE) dose of study intervention * Any condition for which, in the opinion of the investigator, participation would not be in the best interest of the participant (example, compromise the well-being) or that could prevent, limit, or confound the protocol-specified assessments * Participants who receive a live vaccination may be permitted to remain in the study, if approved by the sponsor and study intervention is held for a period of time specified by the sponsor. Receipt of a live severe acute respiratory syndrome coronavirus 2 (SARS CoV-2) vaccine (against the virus that causes Coronavirus Disease 2019 \[COVID-19\]) is not automatically an exclusion criterion and must be discussed with the medical monitor