MS exacerbation; transient low-grade fever; This literature-study case was reported in a literature article and describes the occurrence of MULTIPLE SCLEROSIS (MS exacerbation) in a 44-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.       Previously administered products included for an unreported indication: GLATIRAMER ACETATE and INTERFERON BETA-1A (Patient started intramuscular interferon beta-1a at age 29 but this was poorly tolerated.). Concurrent medical conditions included Optic neuritis, Relapsing-remitting multiple sclerosis (Patient had her first MS symptoms at age 20 when she developed optic neuritis. Patient started intramuscular interferon beta-1a at age 29 but this was poorly tolerated. One year later, she had an episode of myelitis and was place on glatiramer acetate for a few months and was again unable to tolerate injections.Her neurological complaints resolved, and she remained off disease-modifying therapy for the next 14 years with stable disease clinically and by MRI. She had a small gadolinium-enhancing lesion in the right pericallosal white matter reported on brain MRI 2 years prior to this presentation but without any new neurological symptoms, followed by stable subsequent imaging) and Myelitis.   On 24-Jan-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. In 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 MULTIPLE SCLEROSIS (MS exacerbation) (seriousness criterion medically significant) and PYREXIA (transient low-grade fever). The patient was treated with GLATIRAMER ACETATE for Myelitis, at an unspecified dose and frequency and METHYLPREDNISOLONE (intravenous) for Adverse event, at a dose of 1000 UNK, qd, 3 days. In 2021, MULTIPLE SCLEROSIS (MS exacerbation) had resolved. At the time of the report, PYREXIA (transient low-grade fever) had resolved.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Disability assessment scale: 1.5 edss score (abnormal) On exam, she had an EDSS score of 1.5 with mild right deltoid and iliopsoas weakness, brisk deep tendon reflexes, and slightly diminished sensation to pinprick in the left back., 0 (normal) Expanded Disability Status Scale (EDSS) -0 and 0 (normal) Expanded Disability Status Scale (EDSS) -0. On an unknown date, Magnetic resonance imaging: abnormal (abnormal) MRI, 1 day after symptom onset, showed a new enhancing lesion in the brain. the new brain enhancing lesion was 1, abnormal Had a small gadolinium-enhancing lesion in the right pericallosal white matter reported on brain MRI 2 years prior to this presentation but without any new neurological symptoms, followed by stable subsequent imaging. and brain t2 lesion was 1 and new spinal cord t2 lesio brain t2 lesion was 1 and new spinal cord t2 lesions was 0.     For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter considered MULTIPLE SCLEROSIS (MS exacerbation) and PYREXIA (transient low-grade fever) to be possibly related.    It was reported that MS disease duration was 24 years  Time since last clinical relapse happened was 14years  Patient had new neurologic symptoms including numbness that ascended from her feet to the middle of her waist without any bowel or bladder incontinence.  Patient was treated with 3 days of 1000 mg IVMP and 30 days later, the neurologic exam returned to normal (EDSS 0). She was started on disease-modifying therapy.  Patient reported that she developed new neurological symptoms including numbness that ascended from her feet to the  middle of her waist without any bowel or bladder incontinence and right sided weakness.  This case concerns a 44-year-old female patient with a previous relevant medical history of Relapsing-remitting multiple sclerosis, who experienced the unexpected event of Multiple sclerosis exacerbation after (mRNA- 1273 vaccine). The event occurred approximately 6 days after the second dose. The rechallenge was not applicable, as the event was reported exclusively after the second dose. The event was considered related to the product per the reporter's assessment. Previous history of Relapsing-remitting multiple sclerosis remains a confounder. The benefit-risk relationship of vaccine is not affected by this report   This case was linked to MOD-2021-318375, MOD-2021-318473 (Patient Link).   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 and does not contain any new information.; Sender's Comments: This case concerns a 44-year-old female patient with a previous relevant medical history of Relapsing-remitting multiple sclerosis, who experienced the unexpected event of Multiple sclerosis exacerbation after (mRNA- 1273 vaccine). The event occurred approximately 6 days after the second dose. The rechallenge was not applicable, as the event was reported exclusively after the second dose. The event was considered related to the product per the reporter's assessment. Previous history of Relapsing-remitting multiple sclerosis remains a confounder. The benefit-risk relationship of vaccine is not affected by this report