Inclusion Criteria:  Men and women aged 18 to 65 years inclusive Patients who have signed written informed consent.  Patients stable on current MS DMT for >6 months including:  Natalizumab (received a minimum of 6 doses per USPI) Fumarates (dimethyl fumarate or diroximel fumarate) Interferon Beta 1a (or pegylated Interferon Beta-1a) Ocrelizumab (received a minimum of 2 full cycles per USPI)  Exclusion Criteria:  Known history of SARS-CoV-2 infection Is pregnant or breastfeeding ≤6 months on current therapy (MS Participants) Participation in another investigational study Recent immunization with a non-COVID vaccine (within 4 weeks) Known or suspected allergy or history of anaphylaxis or other significant adverse reaction to the COVID-19 vaccine or its excipients Absolute lymphocyte count <0.5 x 10^9/L Concurrent Intravenous or Subcutaneous Immunoglobulin treatment (IVIG/SCIG) Received systemic corticosteroids < 30 days prior to Vaccine Dose 1  Visit and Assessment Schedule:  Participants will agree to five visits during the study and serum will be collected at the following time points:  Baseline/Screening visit 8 weeks after 1st dose/4 weeks after 2nd dose (+/- 1 week) 24 weeks (+/- 2 weeks) 48 weeks (+/- 4 weeks) 72 weeks (+/- 4 weeks)  Approximately 20ml of blood will be collected per patient per each visit.  Data Collection Plan and Patient Privacy Protection Prior to any testing under this protocol, including screening tests and assessments, candidates must also provide all authorizations required by local law (e.g., PHI authorization in North America).  The subject will not be identified by name in the CRF or in any study reports, and these reports will be used for research purposes only. Ethics committees and various government health agencies may inspect the records of this study. Every effort will be made to keep the subject's personal medical data confidential.