Encephalopathy; Non-convulsive focal status epilepticus; visual hallucinations; acute confusion; left frontal headache; urinary tract infection; This case was reported in a literature article and describes the occurrence of ENCEPHALOPATHY (Encephalopathy), STATUS EPILEPTICUS (Non-convulsive focal status epilepticus), HALLUCINATION, VISUAL (visual hallucinations), CONFUSIONAL STATE (acute confusion) and HEADACHE (left frontal headache) in an 86-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.     The patient's past medical history included Diastolic dysfunction, Type 2 diabetes mellitus, Phacoemulsification and Lens implant. Concurrent medical conditions included Chronic kidney disease stage 3, Glaucoma and Cataracts. Concomitant products included PREDNISOLONE for an unknown indication.   On an unknown date, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On an unknown date, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) dosage was changed to 1 dosage form. On an unknown date, the patient experienced ENCEPHALOPATHY (Encephalopathy) (seriousness criteria hospitalization prolonged and medically significant), STATUS EPILEPTICUS (Non-convulsive focal status epilepticus) (seriousness criteria hospitalization prolonged and medically significant), HALLUCINATION, VISUAL (visual hallucinations) (seriousness criteria hospitalization prolonged and medically significant), CONFUSIONAL STATE (acute confusion) (seriousness criterion hospitalization prolonged), HEADACHE (left frontal headache) (seriousness criterion hospitalization prolonged) and URINARY TRACT INFECTION (urinary tract infection). The patient was hospitalized from sometime in 2021 to sometime in 2021 due to CONFUSIONAL STATE, ENCEPHALOPATHY, HALLUCINATION, VISUAL, HEADACHE and STATUS EPILEPTICUS. The patient was treated with CEFALEXIN MONOHYDRATE (CEPHALEXIN [CEFALEXIN MONOHYDRATE]) for Urinary tract infection, at an unspecified dose and frequency; CEFTRIAXONE for Adverse event, at an unspecified dose and frequency; LORAZEPAM for Adverse event, at an unspecified dose and frequency and FOSPHENYTOIN for Adverse event, at an unspecified dose and frequency. At the time of the report, ENCEPHALOPATHY (Encephalopathy), STATUS EPILEPTICUS (Non-convulsive focal status epilepticus), HALLUCINATION, VISUAL (visual hallucinations), CONFUSIONAL STATE (acute confusion), HEADACHE (left frontal headache) and URINARY TRACT INFECTION (urinary tract infection) had resolved.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): In 2021, Blood culture: negative (Negative) Negative. In 2021, Blood folate: normal (normal) normal. In 2021, Blood gases: normal (normal) unremarkable. In 2021, Blood glucose: high (High) 394 mg/dL with an osmolality of 308 mOsm/kg.. In 2021, Blood thyroid stimulating hormone: normal (normal) normal. In 2021, C-reactive protein: borderline (Borderline) 1.2 mg/dL and high (High) 4.0 mg/dL. In 2021, CSF culture: negative (Negative) Negative. In 2021, CSF test: negative (Negative) meningitis/encephalitis panel NAAT, oligoclonal bands and Lyme antibody were negative except for West Nile virus IgG but no IgM antibodies with minimal protein elevation. In 2021, Chest X-ray: normal (normal) unremarkable. In 2021, Computerised tomogram: normal (normal) no acute findings. In 2021, Culture urine: negative (Negative) Negative. In 2021, Electroencephalogram: abnormal (abnormal) non-convulsive focal status epilepticus. In 2021, Magnetic resonance imaging head: normal (normal) with and without contrast showed no acute findings.. In 2021, Metabolic function test: normal (normal) normal. In 2021, Physical examination: abnormal (abnormal) Word finding difficulties and slow mentation. however, no focal neurological deficits noted. No suprapubic, abdominal nor costovertebral pain was noted.. In 2021, Procalcitonin: borderline (Borderline) 0.14 ng/ml. In 2021, Red blood cell sedimentation rate: high (High) 107 mm/hr. In 2021, Respiratory tract infection: normal (normal) normal. In 2021, SARS-CoV-2 test: normal (normal) normal. In 2021, Treponema test: negative (Negative) Negative. In 2021, Urine analysis: negative (Negative) Negative. In 2021, Vital signs measurement: borderline (Borderline) Body temperature: afebrile, Pulse 61, respiratory rate 20, oxygen saturation 99% on room air Blood pressure 150-170/66-75. In 2021, Vitamin B1: normal (normal) normal. In 2021, Vitamin B12: elevated (High) above 2000 pg/mL.     mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) dosing remained unchanged.   For mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular), the reporter considered ENCEPHALOPATHY (Encephalopathy), STATUS EPILEPTICUS (Non-convulsive focal status epilepticus), HALLUCINATION, VISUAL (visual hallucinations), CONFUSIONAL STATE (acute confusion) and HEADACHE (left frontal headache) to be possibly related. No further causality assessment was provided for URINARY TRACT INFECTION (urinary tract infection).    Patient was at baseline neurological function. Patient had no evidence of cognitive dysfunction at baseline and no known neurological or psychiatric history. Patient had never used tobacco, alcohol nor any other illicit drugs. Their was no evidence of giant cell arteritis. Patient had no family history of seizures. Patient was seen in outpatient neurology clinic one month post hospitalization with baseline neurological status. Patient also reported she received 2nd Moderna vaccine 2 weeks post hospitalization and only experienced local injection soreness.  Based on the current available information and temporal association between the use of the product and the start date of the events, a causal relationship cannot be excluded. This is a literature case.   This case was linked to MOD-2021-256855, MOD-2021-256858 (Patient Link).; Sender's Comments: Based on the current available information and temporal association between the use of the product and the start date of the events, a causal relationship cannot be excluded. This is a literature case.