Key Inclusion Criteria:  Diagnosis of MS according to McDonald criteria (2018) SARS-CoV-2 vaccination is planned (within the upcoming 90 days), underway (only one of two vaccinations received) or only recently completed (in the last 6 weeks) or SARS-CoV-2 vaccination has been completed >6 weeks but an additional vaccination is planned within the upcoming 30 days  Key Exclusion Criteria:  Participant cannot be regularly followed up for organizational or geographic reasons Participant is unwilling to get vaccinated against SARS CoV-2 virus  NOTE: Other protocol defined Inclusion/Exclusion criteria may apply.