United States of America (USA) specific inclusion criterion: - Participant must be 12 to <18 years of age at the time of signing the Informed consent/assent according to local regulation Rest of world (ROW) specific inclusion criterion: - Participant must be 2 to <18 years of age at the time of signing the Informed consent/assent according to local regulation Global inclusion criteria: - Participant has a diagnosis of generalized myasthenia gravis (gMG) confirmed by a prior positive serologic test result to acetylcholine receptor (AChR) prior to Screening - Participant meets the criteria as defined by the Myasthenia Gravis Foundation of America (MGFA) Clinical Classification II to IV at Screening - Participants with gMG, including: - An MG-activities of daily living (MG-ADL) total score of 6 or more in adolescents from 12 years to <18 years of age at Screening - Documented weakness in at least 1 limb, neck, or bulbar muscle in children from 2 years to <12 years of age at Screening (does not apply to US) - Documented vaccination against meningococcal infections within 3 years prior to study start. If not fully vaccinated, participants must receive appropriate prophylactic antibiotic treatment until at least 2 weeks after the initial dose of vaccine(s)