A warning is included in the prescribing information and medication guide for those therapies. PML has occurred very rarely in people using some MS disease modifying therapies. Testing positive for the JC virus does not mean you will develop PML, though it could put you at higher risk if you take medications that weaken your immune system.

The JC virus causes no symptoms and is usually managed by the immune system without any treatment. Progressive multifocal leukoencephalopathy (PML) is a rare, progressive white matter brain disease that targets cells that make myelin and usually leads to severe disability or death. PML is caused by the reactivation of the JC (John Cunningham) virus, a common virus to which most people have been exposed. MS disease modifying therapies and progressive multifocal leukoencephalopathy (PML) For help with DMT costs, read about pharmaceutical companies’ patient assistance programs. Under certain circumstances, some healthcare providers may use medications to treat MS that have FDA approval for other diseases – read more about 'off-label' use. Dimethyl Fumarate (dimethyl fumarate - generic equivalent of Tecfidera).Glatopa® (glatiramer acetate - generic equivalent of Copaxone 20mg and 40mg doses).Glatiramer Acetate Injection (glatiramer acetate -generic equivalent of Copaxone 20 mg and 40 mg doses).The following US Food and Drug Administration (FDA) approved disease modifying therapies for MS have been found through clinical trials to reduce the number of relapses, delay progression of disability, and limit new disease activity (as seen on MRI). d Disease Modifying Therapy Guidance During COVID-19.Evusheld to Prevent COVID-19 in People with MS.d Medicines to Prevent and Treat COVID-19.COVID-19 Vaccines for Children and Adolescents with MS and Related Disorders.Timing MS Medications with COVID-19 Vaccines.d COVID-19 Vaccine Guidance for People Living with MS.COVID-19 Information for Healthcare Providers.Resources and Services for Your Patients.Scientific Peer Reviewers & Advisory Committees.d Diversity, Equity and Inclusion and the National MS Society.Independent Review of Society's Research Programs.How and Why Do Scientists Share Results.Research Studies: Newly Diagnosed with MS.COVID-19 Studies Recruiting People with MS.Multiple Sclerosis and the Americans with Disabilities Act (ADA).d Find Programs & Services in Your Area.Resilience: Addressing the Challenges of MS.Cumbre de Esclerosis Múltiple para Hispanos/Latinx.d aHSCT in MS (Autologous Hematopoietic Stem Cell Transplantation).d Complementary & Alternative Medicines.Functional Electrical Stimulation (FES).Make the Most of Your Healthcare Provider Visits.Acute Disseminated Encephalomyelitis (ADEM).