newly diagnosed RRMS; This literature-study case was reported in a literature article and describes the occurrence of RELAPSING-REMITTING MULTIPLE SCLEROSIS (newly diagnosed RRMS) in a 26-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination.     No Medical History information was reported.   On 27-Dec-2020, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On 25-Jan-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. In 2021,  after starting mRNA-1273 (Moderna COVID-19 Vaccine), the patient experienced RELAPSING-REMITTING MULTIPLE SCLEROSIS (newly diagnosed RRMS) (seriousness criterion medically significant). The patient was treated with METHYLPREDNISOLONE (intravenous) in February 2021 for Relapsing-remitting multiple sclerosis, at a dose of 1000 milligram. At the time of the report, RELAPSING-REMITTING MULTIPLE SCLEROSIS (newly diagnosed RRMS) had resolved.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On 26-Jan-2021, SARS-CoV-2 test: negative (Negative) Patient had a negative COVID-19 nasal PCR test one day after the second vaccine dose. In February 2021, Blood glucose (70 mg/dl-110 mg/dl): 131 mg/dl (High) Serum glucose- 131 mg/dL. In February 2021, CSF glucose (50 mg/dl-75 mg/dl): 94 mg/dl (High) Glucose- 94 mg/dL. In February 2021, CSF immunoglobulin (Unknown-= 0.85): 1.27 (High) elevated IgG index (CSF/serum) at 1.27. In February 2021, CSF lymphocyte count (0-100%): 91% (normal) Lymphocytes- 91%. In February 2021, CSF monocyte count (0-100%): 5% Monocytes- 5%. In February 2021, CSF neutrophil count (0%-Unknown): 0% Neutrophils- 0%. In February 2021, CSF oligoclonal band: 0 (normal) Oligoclonal bands-0. In February 2021, CSF protein (5 mg/dl-55 mg/dl): 19 mg/dl (normal) Total protein- 19 mg/dL. In February 2021, CSF red blood cell count (0 /ul-5 /ul): 7 /ul (High) RBC- 7 /uL. In February 2021, CSF white blood cell count (0 /ul-5 /ul): 19 /ul (High) WBC count- 19 /uL. In February 2021, Neurological examination: normal (normal) At follow-up visit, 14 days after symptom onset, she had returned to baseline and neurologic examination was normal.. In September 2021, SARS-CoV-2 antibody test: positive (Positive) showed a positive serum SARS-CoV-2 spike antibody, suggesting humoral immunity to the SARS-CoV-2 virus, when checked 8 months after completing COVID-19 vaccination (608.70 U/mLnegative < 0.80 U/mL).. On an unknown date, Antibody test: unremarkable (normal) Lyme titer was unremarkable. On an unknown date, Antineutrophil cytoplasmic antibody: unremarkable (normal) anti-neutrophil cytoplasmic antibody was unremarkable.. On an unknown date, Antinuclear antibody: unremarkable (normal) antinuclear antibody was unremarkable. On an unknown date, Expanded disability status scale: 0 EDSS score at baseline was 0 and EDSS score after treatment was also 0. On an unknown date, Magnetic resonance imaging: abnormal (abnormal) MRI showed multiple T2 hyperintense periventricular, subcortical, posterior fossa, and spinal cord lesions with morphology suggesting MS. After gadolinium administration, two of the lesions enhanced (one each in the brain and spinal cord). New brain T2 lesions was 9 and New spinal cord T2 lesions was >2. On an unknown date, Ophthalmological examination: abnormal (abnormal) relative afferent pupillary defect (RAPD) and color desaturation OD.. On an unknown date, Visual acuity tests: decreased decreased visual acuity (20/50). On an unknown date, Visual field tests: abnormal (abnormal) Visual field assessment showed a monocular central/inferior monocular deficit.     For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter considered RELAPSING-REMITTING MULTIPLE SCLEROSIS (newly diagnosed RRMS) to be possibly related.    Concomitant product use was not provided by the reporter.    Patient did not have history of COVID-19 infection and  no significant past medical history.  Patient presented with 2 days of new visual symptoms involving the right eye. Her symptoms began with mild blurring, which progressed over the next few days to worsening blurriness and pain with eye movement OD (right eye).  Patient received the second dose 29 days after the first dose without any significant immediate side effects after vaccination.  Lumbar puncture was performed 4 days after symptom onset. The CSF was otherwise normal on protein and glucose, without oligoclonal bands.  Patient received 5 days of 1000 mg IVMP, 3 days after symptom onset, leading to gradual improvement of her symptoms. Given her clinical presentation and MRI findings, she was diagnosed with RRMS and started MS disease-modifying therapy.  Company Comment: This literature report concerns a 26 year old female patient with no relevant medical history who developed a new onset unexpected serious event of relapsing-remitting multiple sclerosis (RMMS) 14 days after vaccination with second dose of mRNA-1273. The patient was treated with 5 days of 1000 mg IV Methylprednisolone with gradual improvement of her symptoms and return to baseline (at 14 days after the symptom onset). The patient was also put on multiple sclerosis (MS) disease-modifying therapy. Based on the current available information and temporal association between the use of the product and the start date of the event, a causal relationship cannot be excluded. The benefit-risk relationship of mRNA-1273  is not affected by this report.   This case was linked to MOD-2021-318375, MOD-2021-318474.   Most recent FOLLOW-UP information incorporated above includes: On 14-Sep-2021: Follow up received by safety on 15-Sep-2021 included an Email received from Team and does not contain any new information.; Sender's Comments: This literature report concerns a 26 year old female patient with no relevant medical history who developed a new onset unexpected serious event of relapsing-remitting multiple sclerosis (RMMS) 14 days after vaccination with second dose of mRNA-1273. The patient was treated with 5 days of 1000 mg IV Methylprednisolone with gradual improvement of her symptoms and return to baseline (at 14 days after the symptom onset). The patient was also put on multiple sclerosis (MS) disease-modifying therapy. Based on the current available information and temporal association between the use of the product and the start date of the event, a causal relationship cannot be excluded. The benefit-risk relationship of mRNA-1273  is not affected by this report.