The purpose of this US FDA post-marketing commitment study is to evaluate the safety of MenACWY-CRM among 50.000 vaccinated adolescents within a large US Healthcare Maintenance Organization who received MenACWY-CRM vaccination as part of their routine clinical care. The pre-specified 26 events of interest are events commonly evaluated in vaccine safety studies and include certain neurological, immunological, vascular, musculoskeletal and hematologic disorders. All events are collected retrospectively.

This is an observational study, vaccines administration and data that is collected is only as part of routine clinical care. Vaccinated subjects are not actively recruited.

Events of interest: Seizure, Aseptic meningitis, Bell's Palsy, Multiple Sclerosis, Guillain-Barre Syndrome, Acute disseminated encephalomyelitis, Cerebellar ataxia, Transverse myelitis, Brachial Neuritis, Hashimoto's disease, Systemic Lupus Erythematosis, Henoch Schonlein Purpura, New Onset Juvenile Diabetes Mellitus, Rheumatoid arthritis, Idiopathic Thrombocytopenic Purpura, Iridocyclitis, Acute glomerulonephritis, Nephrotic syndrome, Grave's disease, Autoimmune hemolytic anemia, Myasthenia Gravis, New onset asthma, Allergic urticaria, Anaphylaxis, Meningococcal Disease, Suicide attempt.

Inclusion Criteria:

1. Enrolled in the HMO for at least 6 months prior to vaccination
2. Between the ages of 11 and 21 years (inclusive - i.e. has not reached their 22nd birthday) at the time of the vaccination.
3. Received the vaccine during the study period

Exclusion Criteria:

The study population is selected from the Health Maintenance Organization population of the Kaiser Permanente Southern California (KPSC) HMO in Pasadena, CA, USA.