multiple sclerosis; This literature-non-study case was reported in a literature article and describes the occurrence of MULTIPLE SCLEROSIS (multiple sclerosis) in a 46-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination.      The patient's past medical history included Optic neuritis (Unilateral optic neuritis at age 38.).    On an unknown date, the patient received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On an unknown date, the patient experienced MULTIPLE SCLEROSIS (multiple sclerosis) (seriousness criteria hospitalization and medically significant). The patient was treated with METHYLPREDNISOLONE (intravenous) for Adverse event, at an unspecified dose and frequency and ACYCLOVIR [ACICLOVIR] for Shingles, at an unspecified dose and frequency. At the time of the report, MULTIPLE SCLEROSIS (multiple sclerosis) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Antinuclear antibody: negative (Negative) Negative. On an unknown date, Magnetic resonance imaging head: abnormal (abnormal) Brain MRI was notable for periventricular and juxtacortical intracranial lesions with enhancement of the periventricular lesion.. On an unknown date, Magnetic resonance imaging neck: abnormal (abnormal) showed multiple enhancing lesions in the spine consistent with demyelination. On an unknown date, Neurological examination: abnormal (abnormal) examination was notable for mild anisocoria with red desaturation in the right eye, but without afferent pupillary defect..     For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter considered MULTIPLE SCLEROSIS (multiple sclerosis) to be related.    No concomitant medication were reported.  Symptoms were initially treated with acyclovir for possible shingles, but clinical evolution with a left foot drop prompted hospitalization.  The patient developed bilateral arm pain and burning sensation on the left lateral abdomen 3 days after the second dose of mRNA-1273 vaccine.  Infectious disease studies in the CSF included herpes viruses (Herpes simplex, Varicella zoster, Epstein-Barr, Cytomegalo), West Nile virus, Borrelia burgdorferi IgG and IgM, and VDRL. Serum MOG-IgG and AQP4-IgG CBAs were also negative. The patient was diagnosed with MS following negative serum diagnostics for systemic autoimmune diseases and vasculitides. Testing included antinuclear antibody and antiextractable nuclear antigen panels.  Company comment: This is a literature case concerning a 46 year-old, female patient with a history of Optic neuritis, who experienced the serious (due to medically important condition and hospitalization) unexpected, AESI of multiple sclerosis. The patient developed bilateral arm pain and burning sensation on the left lateral abdomen 3 days after the second dose of mRNA-1273 vaccine. Patient was initially treated with acyclovir for possible shingles but the patient developed a left foot drop and was hospitalized. Brain magnetic resonance showed periventricular and juxtacortical intracranial lesions with enhancement of the periventricular lesion. Cervical and thoracic spine MRI showed multiple enhancing lesions in the spine consistent with demyelination. Cerebrospinal fluid analysis demonstrated pleocytosis, elevated IgG index, and 20 unique bands. Diagnosis of multiple sclerosis was made as the infectious and autoimmune panel were negative. She was treated with 5 days of intravenous methylprednisolone. The outcome of the event was not reported. The medical history, of Optic neuritis remains a confounder. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.   This case was linked to MOD-2022-453474, MOD-2022-453440 (Patient Link).; Sender's Comments: This is a literature case concerning a 46 year-old, female patient with a history of Optic neuritis, who experienced the serious (due to medically important condition and hospitalization) unexpected, AESI of multiple sclerosis. The patient developed bilateral arm pain and burning sensation on the left lateral abdomen 3 days after the second dose of mRNA-1273 vaccine. Patient was initially treated with acyclovir for possible shingles but the patient developed a left foot drop and was hospitalized. Brain magnetic resonance showed periventricular and juxtacortical intracranial lesions with enhancement of the periventricular lesion. Cervical and thoracic spine MRI showed multiple enhancing lesions in the spine consistent with demyelination. Cerebrospinal fluid analysis demonstrated pleocytosis, elevated IgG index, and 20 unique bands. Diagnosis of multiple sclerosis was made as the infectious and autoimmune panel were negative. She was treated with 5 days of intravenous methylprednisolone. The outcome of the event was not reported. The medical history, of Optic neuritis remains a confounder. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.