A Study to Provide Complementary Efficacy, Safety and Patient Reported Outcomes Data in Participants With Active Relapsing Forms of Multiple Sclerosis (MS) in a Pragmatic Setting

Inclusion Criteria: * Age \>/=18 years at screening * Patients with relapsing forms of multiple sclerosis (RMS) with active disease defined by clinical or imaging features: (i) at least one clinical relapse over a 6-month period prior to screening; (ii) AND/OR at least one T1 gadolinium-enhancing lesion or new and/or enlarging T2 lesion as detected by brain Magnetic Resonance Imaging (MRI) performed over a 3 months period prior to screening with no change of Disease-Modifying Treatment(s) (DMT) compared to a previous MRI performed within 24 months before screening * For women of childbearing potential: agreement to use an acceptable birth control method during the treatment period and for at least 12 months after the last dose of ocrelizumab * Participants should be beneficiary of healthcare coverage under the social security system Exclusion Criteria: * Diagnosis of primary progressive MS * Inability to complete an MRI (contraindications for MRI include but are not restricted to weight ≥140 kg, pacemaker, cochlear implants, presence of foreign substances in the eye, intracranial vascular clips, surgery within 6 weeks of entry into the study, coronary stent implanted within 8 weeks prior to the time of the intended MRI, etc…) * Gadolinium intolerance * History of ischemic cerebrovascular disorders (e.g., stroke, transient ischemic attack) or ischemia of the spinal cord * History or known presence of central nervous system (CNS) or spinal cord tumor (e.g., meningioma, gliom…