Received Jan 15, 2026
| Type | Name | Manufacturer | Dose | Lot | Route / Site |
|---|---|---|---|---|---|
| RSV | RSV (MRESVIA) | MODERNA | 1 | — | IM / RA |
MULTIPLE SCLEROSIS FLARE; This 76-year-old, Female participant was enrolled in "A Phase 3 Study to Evaluate the Immunogenicity and Safety of mRNA-1345, an mRNA Vaccine Targeting Respiratory Syncytial Virus, in High-risk Adults (mRNA-1345-P303)" and experienced serious (hospitalization) adverse event of multiple sclerosis flare (Multiple sclerosis relapse). The participant's medical history included muscle spasms, diabetes type 2, multiple sclerosis, acid reflux, seasonal allergies, hepatic cirrhosis, hepatic carcinoma, liver transplant, complete hysterectomy, liver cirrhosis. Concomitant medications included gabapentin, tizanidine, acetaminophen, insulin glargine, dapagliflozin propanediol monohydrate, mycophenolate mofetil, tacrolimus, omeprazole, tirzepatide, pitavastatin. Prior to the event onset, the participant received first blinded dose of mRNA-1345, 1 dosage form, on 31-JAN-2024, for respiratory syncytial virus (RSV) immunization, Intramuscular use. The last dose of study drug was received on 25-MAR-2024, approximately 1 year 9 months 3 days before onset of the event. On 29-DEC-2025, the participant experienced multiple sclerosis flare. She presented to the hospital due to multiple falls, visual changes, and worsening weakness over the previous week and was admitted. The neurological exam was notable for left lower extremity greater than right lower extremity weakness, and the participant had blurry or painful vision. Presentation was most consistent with a multiple sclerosis flare. She received treatment of methylprednisolone and prednisone. On that day, magnetic resonance imaging (MRI) head, orbit, neck showed stable appearance and distribution of numerous demyelinating lesions within the predominantly supratentorial white matter. No new or enhancing white matter lesions. the optic nerves appear unremarkable bilaterally. New curvilinear T2/FLAIR signal hyperintensity along the left frontoparietal convexity measuring up to 4 mm in thickness possibly representing a subacute subdural hematoma. No significant mass effect or midline shift. No other acute intracranial abnormality. Computerized tomogram (CT) spine showed no acute lumbar spinal fracture. On 01-JAN-2026, the participant was discharged on prednisone 60 mg for 11 days, followed by a decreased dose by 10 mg every 3 days and then discontinued. The participant received all scheduled doses of study drug prior to the event; therefore, action taken with study drug in response to the event was not applicable. The outcome of event, multiple sclerosis flare was reported as resolving. The investigator assessed the causality of the event, multiple sclerosis flare as not related to mRNA-1345. Medical summary: This 76-year-old female participant with medical history of multiple sclerosis, muscle spasms, and others experienced a serious adverse event of multiple sclerosis flare. This event occurred approximately 21 months after receiving the last dose of mRNA-1345. She presented with multiple falls, visual changes, and worsening weakness over the past week and was admitted to hospital. Neurological exam showed left lower extremity weakness greater than right lower extremity weakness. She also had blurry or painful vision. Presentation was most consistent with a multiple sclerosis flare. She received treatment of methylprednisolone and prednisone. The investigator assessed the causality of the event as not related to the IP. Considering the unfavorable latency and participant's longstanding history of multiple sclerosis, the occurrence of this event is more plausibly attributed to the progression of her disease rather than the study vaccine.; Reporter's Comments: The investigator considered the event multiple sclerosis flare as Not Related to mRNA-1345. The sponsor considered the event multiple sclerosis flare as Not Related to mRNA-1345 considering the unfavorable latency and participant's longstanding history of multiple sclerosis.
Acid reflux (esophageal); Multiple sclerosis; Muscle spasms; Seasonal allergy; Type 2 diabetes mellitus
Medical History/Concurrent Conditions: Hysterectomy; Liver carcinoma; Liver cirrhosis; Liver transplant
Gabapentin; Tizanidine; Acetaminophen; Basaglar; Farxiga; Mycophenolate mofetil; Tacrolimus; Omeprazole; Mounjaro; Pitavastatin
Test Date: 20251229; Test Name: CT spine; Result Unstructured Data: no acute lumbar spinal fracture; Test Date: 20251229; Test Name: MRI head, orbit, neck; Result Unstructured Data: stable appearance and distribution of numerous demyelinating lesions within the predominantly supratentorial white matter. No new or enhancing white matter lesions. the optic nerves appear unremarkable bilaterally. New curvilinear T2/FLAIR signal hyperintensity along the left frontoparietal convexity measuring up to 4 mm in thickness possibly representing a subacute subdural hematoma. No significant mass effect or midline shift. No other acute intracranial abnormality.; Test Date: 20251229; Test Name: neurological examination; Result Unstructured Data: notable for left lower extremity greater than right lower extremity weakness, and the participant had blurry or painful vision