A Study to Evaluate the Efficacy, Safety, Pharmacokinetics, and Pharmacodynamics of Satralizumab in Participants With Myelin Oligodendrocyte Glycoprotein Antibody-associated Disease

Inclusion criteria * Participants who are aged \>=12 years at the time of signing Informed Consent Form * Confirmed diagnosis of MOGAD with a history of \>=1 MOGAD relapse in the 12 months prior to screening or \>=2 attacks in the 24 months prior to screening * Expanded Disability Status Scale (EDSS) score of 0-6.5 at screening * High-contrast visual acuity (HCVA) better than 20/800 in each eye at screening * Participants receiving either no or ongoing chronic immunosuppressant treatment (IST) for MOGAD at the time of screening * For women of childbearing potential: participants who agree to remain abstinent or use adequate contraception during the treatment period and for at least 3 months after the final dose of satralizumab Exclusion criteria * Presence of aquaporin-4-antibodies immunoglobin G (AQP4-IgG) in the serum * History of anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis * Any concomitant disease other than MOGAD that may require treatment with ISTs or oral corticosteroids (OCS) or intravenous (IV) corticosteroids at doses \> 20 milligrams (mg) prednisone equivalent per day for \>21 days during the study * Participants who are pregnant or breastfeeding, or intending to become pregnant during the study or within 3 months after the final dose of satralizumab * Participants with active or presence of recurrent bacterial, viral, fungal, mycobacterial infection, or other infection at baseline * Participants with evidence of latent or active tuberculosis (excluding patients receiving chemoprophylaxis for latent tuberculosis infection) * Participants with positive screening tests for hepatitis B and C * Receipt of live or live attenuated vaccine within 6 weeks prior to baseline * History of severe allergic reaction to a biologic agent