The HIt HArd and hiT Early in Multiple Sclerosis Trial

Inclusion Criteria: * Diagnosis of RRMS according to the 2017 revised McDonald criteria, * With disease activity within the preceding year in the form of: a clinical relapse, and/or evidence of ≥2 T2 lesions on MRI scan, and or presence of gadolinium enhancing lesions on an MRI scan, * Age 18 - 50 years (inclusive) of age, * Disease duration ≤10 years (since MS diagnosis), * EDSS 0 - 5.5 (inclusive), * Signed informed consent. Exclusion Criteria: * Diagnosis of progressive MS, * Previous use of rituximab (or any other B-cell depleting monoclonal antibody) and/or cladribine, * Pregnant or lactating women, * Unwilling to use contraception during the treatment period and the first year after completing the treatment course, * Patients having contraindication for or otherwise not compliant with MRI investigations, * Simultaneous treatment with other immunosuppressive drugs, * Infection with human immunodeficiency virus (HIV), * Active, severe infections (e.g. hepatitis or tuberculosis), * Severe cardiac disorder, * Moderate or severe renal impairment (eGFR \<60). * Active malignancy, * No prior exposure to varicella virus, * Vaccination within 4 weeks of first dose of study medication, * Severe psychiatric condition.