Overview

The primary objective of the study is to estimate the incidence of progressive multifocal leukoencephalopathy (PML) and serious adverse events (SAEs) of other opportunistic infections (OIs) among all participants taking natalizumab. The secondary objectives of the study are to estimate the incidence of SAEs, to estimate the incidence of SAEs among participant subgroups defined by demographic and clinical factors (age, gender, duration of treatment, pregnancy, breastfeeding), to characterize and estimate incidences of malignancies, hypersensitivity reactions and John Cunningham Virus (JCV) positivity among all participants taking natalizumab, and to count and describe pregnancies and breastfeeding among participants previously exposed to natalizumab.

Eligibility

Key Inclusion Criteria:

• Participants starting with natalizumab after 1st January 2019 and participating in the ReMuS will be included in this study

Key Exclusion Criteria:

• Not Applicable (NA)

NOTE: Other protocol defined Inclusion/Exclusion criteria may apply.