Phase IIIB-IV Long-Term Follow-up Study for Patients Who Participated in CAMMS03409

Primary Objective: To evaluate long-term safety of alemtuzumab. Secondary Objectives: * To evaluate long term efficacy of alemtuzumab. * To evaluate the safety profile of participants who received other Disease Modifying Treatment (DMT) following alemtuzumab treatment. * To evaluate participant-reported Quality of Life (QoL) outcomes and health resource utilization of participant who received alemtuzumab. * To evaluate as needed re-treatment with alemtuzumab and other DMTs.

The total duration per participants was up to 5.6 years. As per Study Investigator discretion, participants can be treated with additional courses of alemtuzumab or any commercialized DMTs. All participants who completed CAMMS03409 were allowed into the study, which might include specific vulnerable populations. If the investigator decided to treat a participant with a course of alemtuzumab, appropriate cautionary measures were applied as indicated in the approved labelling, or, in ex-European Union countries where Lemtrada was not approved, according to the investigator's brochure.