Safety, Tolerability, and Immunogenicity of MenABCWY Administered on Different Dosing Schedules in Healthy Adolescents

Inclusion Criteria: * Participants or/and participants' parent(s)/Legally Acceptable Representative(s) \[LAR(s)\] who, in the opinion of the investigator, can and will comply, with the requirements of the protocol. * Written or witnessed/thumb printed informed consent obtained from the participant/parent(s)/LAR(s) of the participant prior to performance of any study specific procedure. * Written informed assent obtained from the participant (if applicable) prior to performing any study specific procedure. * A male or female between, and including, 11 and 14 years of age (i.e. 14 years + 364 days) at the time of the first vaccination. * Healthy participants as established by medical history, physical examination and clinical judgment of the investigator before entering into the study. * Female participants of non-childbearing potential may be enrolled in the study. Non-childbearing potential is defined as pre-menarche, hysterectomy, bilateral-salpingectomy or bilateral ovariectomy. * Female participants of childbearing potential may be enrolled in the study, if the participant: * has practiced adequate contraception for 30 days prior to first vaccination, and * has a negative pregnancy test\* on the day of vaccination, and * has agreed to follow adequate contraception for 30 days before each of the 2 subsequent vaccinations and for 30 days after each vaccination \* Urine samples for pregnancy testing will be collected from female participants of childbearing potential at Visit 1, Visit 3 and Visit 5 prior to the vaccination. Exclusion Criteria: Medical conditions * Current or previous, confirmed or suspected disease caused by N. meningitidis. * Household contact with and/or intimate exposure to an individual with laboratory confirmed N. meningitidis infection within 60 days of enrolment. * Progressive, unstable or uncontrolled clinical conditions. * Clinical conditions representing a contraindication to intramuscular vaccination and blood draws. * Any neuroinflammatory, congenital neurological conditions, encephalopathies, seizures. History of febrile convulsions should not lead to exclusion. * History of any reaction or hypersensitivity likely to be exacerbated by any component of the vaccine(s)/product(s). * Hypersensitivity, including allergy, to any component of vaccines, including diphtheria toxoid (CRM197) and latex medicinal products or medical equipment whose use is foreseen in this study. * Abnormal function or modification of the immune system resulting from: * Autoimmune disorders or immunodeficiency syndromes. * Systemic administration of corticosteroids (PO/IV/IM) for more than 14 consecutive days within 90 days prior to study vaccination. This will mean prednisone equivalent ≥20 mg/day for adult participants / ≥0.5 mg/kg/day with maximum 20 mg/day for paediatric participants. Inhaled and topical steroids are allowed. * Administration of antineoplastic and immunomodulating agents or radiotherapy within 90 days prior to study vaccination. * Administration of long-acting immune-modifying drugs at any time during the study period. * Any other clinical condition that, in the opinion of the investigator, might pose additional risk to the participant due to participation in the study. Prior/Concomitant therapy * Use of any investigational or non-registered product (drug, vaccine or medical device) other than the study vaccine(s)/product(s) during the period starting 30 days before the first dose of study vaccine(s)/product(s) (Day -29 to Day 1), or planned use during the study period. * Previous vaccination with any meningococcal (MenB or MenACWY) vaccine at any time prior to informed consent/ assent (as applicable) with the exception of meningococcal C (conjugated or polysaccharide) vaccination, if the last dose of MenC was received at ≤24 months of age. * Administration of immunoglobulins and/or any blood products or plasma derivatives during the period starting 3 months before the administration of study vaccine/product or planned administration before the next blood sampling visit. * Chronic administration (defined as more than 14 days in total) of immunosuppressants or other immune-modifying drugs during the period starting 90 days prior to the first vaccine/product dose(s). For corticosteroids, this will mean prednisone equivalent ≥20 mg/day for adult participants / ≥0.5 mg/kg/day with maximum of 20 mg/day for paediatric participants. Inhaled and topical steroids are allowed. Prior/Concurrent clinical study experience • Concurrently participating in another clinical study, at any time during the study period, in which the participant has been or will be exposed to an investigational or a non-investigational vaccine/product (drug or medical device). Other exclusions * Child in care. * Pregnant or lactating female. * Female planning to become pregnant / planning to discontinue contraceptive precautions during the windows reported in the inclusion criterion. * History of /current chronic alcohol abuse and/or drug abuse as determined by the investigator. * Any study personnel or immediate dependants, family, or household members.