Evaluation of PK, PD, Efficacy, Safety, and Immunogenicity of IV Ravulizumab in Pediatric Participants With Generalized Myasthenia Gravis

Inclusion Criteria: * Diagnosis of gMG confirmed by a positive serologic test for anti-AChR antibodies (Abs) obtained at Screening and/or during Screening Period * Myasthenia Gravis Foundation of America (MGFA) Clinical Classification of Class II to Class IV at Screening * Participants receiving treatment must be on a stable dosing regimen of adequate duration prior to Screening and during the Screening Period. * Eculizumab-experienced participants must have been enrolled and treated with eculizumab in Study ECU-MG-303 for at least 6 months (180 days) and must have been on a stable dose for ≥ 2 months (60 days) prior to Screening. * All participants must be vaccinated against meningococcal infection Exclusion Criteria: Medical Conditions * Any untreated thymic malignancy, carcinoma, or thymoma. * Participants with a history of treated benign thymoma * History of thymectomy, thymomectomy, or any thymic surgery within the 12 months prior to Screening * History of N meningitidis infection * Known to be human immunodeficiency virus (HIV) positive * History of unexplained infections * Known or suspected history of drug or alcohol abuse or dependence within 1 year prior to the start of the Screening Period