A Study to Evaluate the Safety of Administering Ocrelizumab Per a Shorter Infusion Protocol in Participants With Primary Progressive Multiple Sclerosis (PPMS) and Relapsing Multiple Sclerosis (RMS)

Inclusion Criteria: * Eligible to receive ocrelizumab per the United States Package Insert (USPI) * Able to comply with the study protocol, in the investigator's judgment * Age 18-55 years, inclusive * Have a diagnosis of PPMS or RMS, confirmed per the revised 2017 McDonald criteria * Expanded Disability Status Scale (EDSS) score of 0 to 6.5, inclusive * For women of childbearing potential: agreement to remain abstinent (refrain from heterosexual intercourse) or use contraceptive methods that result in a failure rate of \<1% per year during the treatment period and for at least 6 months after the last dose of study treatment (per the USPI) Exclusion Criteria: * Experienced serious IRR(s) * History of life-threatening infusion reaction to ocrelizumab * Known presence of other neurological disorders * Pregnancy or lactation, or intention to become pregnant during the study * Any concomitant disease that may require chronic treatment with systemic corticosteroids or immunosuppressants during the course of the study * Significant, uncontrolled disease, such as cardiovascular (including cardiac arrhythmia), pulmonary (including obstructive pulmonary disease), renal, hepatic, endocrine, and gastrointestinal or any other significant disease that may preclude patient from participating in the study * Congestive heart failure * Known active bacterial, viral, fungal, mycobacterial infection or other infection or any severe episode of infection requiring hospitalization or treatment with IV antibiotics within 4 weeks prior to baseline visit or oral antibiotics within 2 weeks prior to baseline visit * History of or currently active primary or secondary immunodeficiency * History or known presence of recurrent or chronic infection (e.g., HIV, syphilis, tuberculosis) * History of recurrent aspiration pneumonia requiring antibiotic therapy * History of malignancy, including solid tumors and hematological malignancies,except basal cell, in situ squamous cell carcinoma of the skin, and in situ carcinoma of the cervix of the uterus that have been excised with clear margins * History of severe allergic or anaphylactic reactions to humanized or murine monoclonal antibodies * History of alcohol or drug abuse within 24 weeks prior to enrollment * Receipt of a live vaccine within 6 weeks prior to enrollment * Systemic corticosteroid therapy within 4 weeks prior to enrollment * Contraindications to or intolerance of oral or IV corticosteroids, including IV methylprednisolone (or equivalent steroid) administered according to the country label * Treatment with alemtuzumab * Treatment with a B-cell targeted therapies other than ocrelizumab * Treatment with a drug that is experimental * Abnormal laboratory results per local laboratory standards and investigator assessment