This week AstraZeneca’s coronavirus vaccine trial was halted because one patient developed an unexpected adverse event called transverse myelitis, which is a broad term for inflammation of the spinal cord. Transverse myelitis has been rarely seen after certain vaccinations as well as after some viral infections. It is also commonly seen in patients with multiple sclerosis. While transverse myelitis from a vaccine is usually a one-time event (as opposed to ongoing inflammation in MS), it can cause a number of symptoms, including weakness, numbness and changes in bladder and bowel function. This is an unfortunate event in terms of the development of a vaccine to coronavirus, but is additionally concerning to MS patients because the complication involved the body’s own immune system causing damage to the spinal cord. When a vaccine for coronavirus vaccine is eventually approved, we will further evaluate its safety in patients with MS.