MS PATHS COVID-19 Questionnaire Data Linkage Sub-Study

Key Inclusion Criteria: 1. Be enrolled in MS PATHS under Study 888MS001. 2. Completed one or more COVID-19 questionnaire at a participating MS PATHS institution. 3. Permission for data linkage either obtained when completing a local COVID-19 questionnaire or granted by waiver of informed consent from the local institutional review board (IRB) or ethics committee (EC). Key Exclusion Criteria: 1\. Other unspecified reasons that, in the opinion of the Investigator or Biogen, make the participant unsuitable for participation in the sub-study. A participant only needs to complete the assessments deemed necessary by the Investigator. Note: Other protocol defined Inclusion/Exclusion criteria may apply.