- Multiple sclerosis (MS) is a complex disease of the central nervous system that affects approximately 400,000 people in the US and 2.5 million worldwide, causing symptoms like blurred vision, weakness, and tingling. MS results from damage to the myelin sheath surrounding nerves in the brain and spinal cord. - Rebif is a treatment for relapsing forms of MS, including relapsing-remitting MS, primary progressive MS, and secondary progressive MS. It is administered via injection three times per week and works to reduce relapses and delay disability progression. Common side effects include injection site reactions, headache, fatigue, and depression. - Notable people living with MS, like hockey player Jordan Sig