The purpose of this study is to provide evidence as to whether RZV is immunogenic with an acceptable safety profile in Multiple Sclerosis patients on anti-CD20 treatment.

In this monocentric study, we will assess the immunogenicity and safety of two doses of the adjuvanted recombinant Zoster vaccine (RZV, or Shingrix®) in Multiple sclerosis patients treated with anti-CD20 (ocrelizumab, group 1) compared to healthy controls (group 2).

Participants will receive Shingrix® on Day0 and Day60; immunological response will be assessed on Day 0, 1, Day 60, 61, Day90 and Day360.

Unsolicited Adverse events of special interest (AESI) will be collected throughout the study period; patients reported outcomes (PROs) will be declared for one week after each vaccination. Safety of MS patients will be monitored through EDSS scoring and MRI before and 1 month after vaccination (D90) and at day 180 and 360 (EDSS scoring only)

Inclusion Criteria:

For MS patients:

• 18 years and above
• Diagnosed with relapsing MS according to McDonald Criteria (2017)
• Not already vaccinated by RZV and willing to be vaccinated with RZV.
• At least 1 year on anti-CD20 treatment: 2 initial infusions of Ocrelizumab 300 mg (2 weeks apart), one infusion of Ocrelizumab 600 mg 6 months apart, one infusion of Ocrelizumab 600 mg 12 months after initial infusions
• Informed consent as documented by signature

For healthy controls

• Aged 50 to 59
• Not already vaccinated by RZV and willing to be vaccinated with RZV
• Informed consent as documented by signature

Exclusion Criteria:

• Recent MS relapse in the 6 weeks preceding planned vaccination
• Ongoing signs of febrile or non-febrile infection at the time of vaccination
• Recent pregnancy with delivery in the six months preceding vaccination and/or planned pregnancy in the six months following RZV vaccination
• Immunosuppression from the following: HIV infection, current active systemic auto-immune disease (other than MS), current malignant neoplasm; primary immunodeficiency; recent solid or bone-marrow transplant or any transplant still requiring immunosuppressive therapy; conditions requiring medication with immunosuppressive drugs
• Having received a vaccine in the last month
• Having received a shingles vaccine within one year
• Presented with herpes zoster in the previous year
• Contra-indication to RZV
• Unable to provide informed consent or inability to follow the procedures of the study, e.g. due to language problems, psychological disorders, dementia.
• Participation in another study with investigational drug within the 30 days preceding and during the present study.