Acute transient encephalopathy/transient inflammatory encephalopathy; This literature-non-study case was reported in a literature article and describes the occurrence of ENCEPHALOPATHY (Acute transient encephalopathy/transient inflammatory encephalopathy) in a 69-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination.       The patient's past medical history included COVID-19 (12 months before the vaccine injection) in March 2022 and Hemodialysis. Concurrent medical conditions included Hypertension, End stage renal disease, Diabetes and Atrial fibrillation. Concomitant products included INSULIN for Diabetes, NYSTATIN (STATIN [NYSTATIN]) for an unknown indication.    On an unknown date, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On an unknown date, the patient experienced ENCEPHALOPATHY (Acute transient encephalopathy/transient inflammatory encephalopathy) (seriousness criteria hospitalization and medically significant). At the time of the report, ENCEPHALOPATHY (Acute transient encephalopathy/transient inflammatory encephalopathy) had resolved.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Alanine aminotransferase (7 u/l-52 u/l): 9 u/l (normal) day 1 of hospitalization 9 U/L, 9 u/l (normal) day 3 of hospitalization 9 U/L, 12 u/l (normal) day 4 of hospitalization 12 U/L and 10 u/l (normal) day 5 of hospitalization 10 U/L. On an unknown date, Ammonia (18 µmol/l-72 µmol/l): 24 µmol/l (normal) day 3 of hospitalization 24 µmol/L. On an unknown date, Aspartate aminotransferase (13 u/l-39 u/l): 14 u/l (normal) day 1 of hospitalization 14 U/L, 17 u/l (normal) day 3 of hospitalization 17 U/L, 14 u/l (normal) day 4 of hospitalization 14 U/L and 11 u/l (abnormal) day 5 of hospitalization 11 U/L. On an unknown date, Blood albumin (3.5 g/dl-5.7 g/dl): 3.8 g/dl (normal) day 1 of hospitalization 3.8 g/dL, 3.5 g/dl (normal) day 3 of hospitalization 3.5 g/dL, 3.5 g/dl (normal) day 4 of hospitalization 3.5 g/dL and 3.4 g/dl (Low) day 5 of hospitalization 3.4 g/dL. On an unknown date, Blood alkaline phosphatase (34 u/l-104 u/l): 127 u/l (High) day 1 of hospitalization 127 U/L, 107 u/l (High) day 3 of hospitalization 107 U/L, 102 u/l (normal) day 4 of hospitalization 102 U/L and 98 u/l (normal) day 5 of hospitalization 98 U/L. On an unknown date, Blood calcium (8.2 mg/dl-10 mg/dl): 9.2mg/dl (normal) day 2 of hospitalization 9.2mg/dL, 8.7 mg/dl (normal) day 3 of hospitalization 8.7 mg/dL, 9.3 mg/dl (normal) day 4 of hospitalization 9.3 mg/dL and 8.8 mg/dl (normal) day 5 of hospitalization 8.8 mg/dL. On an unknown date, Blood creatinine (0.6 mg/dl-1.3 mg/dl): 7.8 mg/dl (High) day 1 of hospitalization 7.8 mg/dL, 6.4 mg/dl (High) day 2 of hospitalization 6.4 mg/dL, 6.9 mg/dl (High) day 3 of hospitalization 6.9 mg/dL, 6.9 mg/dl (High) day 4 of hospitalization 6.9 mg/dL and 5.1 mg/dl (High) day 5 of hospitalization 5.1 mg/dL. On an unknown date, Blood culture: 2 sets no growth day 3 of hospitalization 2 sets no growth. On an unknown date, Blood glucose (70 mg/dl-99 mg/dl): 120 mg/dl (High) day 1 of hospitalization 120 mg/dL, 151 mg/dl (High) day 2 of hospitalization 151 mg/dL, 128 mg/dl (High) day 3 of hospitalization 128 mg/dL, 111 mg/dl (High) day 4 of hospitalization 111 mg/dL and 152 mg/dl (High) day 5 of hospitalization 152 mg/dL. On an unknown date, Blood magnesium (1.9 mg/dl-2.7 mg/dl): 2.1 mg/dl (normal) day 2 of hospitalization 2.1 mg/dL, 2.1 mg/dl (normal) day 3 of hospitalization 2.1 mg/dL and 2.3 mg/dl (normal) day 4 of hospitalization 2.3 mg/dL. On an unknown date, Blood phosphorus (2.5 mg/dl-5 mg/dl): 4.3 mg/dl (normal) day 2 of hospitalization 4.3 mg/dL, 4.5 mg/dl (normal) day 3 of hospitalization 4.5 mg/dL and 4.9 mg/dl (normal) day 4 of hospitalization 4.9 mg/dL. On an unknown date, Blood potassium (3.5 mmol/l-5.1 mmol/l): 5.4 mmol/l (High) day 1 of hospitalization 5.4 mmol/L, 4.4 mmol/l (normal) day 2 of hospitalization 4.4 mmol/L, 4.6 mmol/l (normal) day 3 of hospitalization 4.6 mmol/L, 4.9 mmol/l (normal) day 4 of hospitalization 4.9 mmol/L and 3.3 mmol/l (abnormal) day 5 of hospitalization 3.3 mmol/L. On an unknown date, Blood sodium (136 mmol/l-145 mmol/l): 134 mmol/l (Low) day 1 of hospitalization 134 mmol/L, 136 mmol/l (normal) day 2 of hospitalization 136 mmol/L, 135 mmol/l (normal) day 3 of hospitalization 135 mmol/L, 142 mmol/l (normal) day 4 of hospitalization 142 mmol/L and 137 mmol/l (normal) day 5 of hospitalization 137 mmol/L. On an unknown date, Blood thyroid stimulating hormone (0.38 µiu/ml-4.7 µiu/ml): 0.91 µiu/ml (normal) day 1 of hospitalization 0.91 µIU/mL and 0.91 µiu/ml (normal) day 2 of hospitalization 0.91 µIU/mL. On an unknown date, Blood urea (7 mg/dl-25 mg/dl): 47 mg/dl (High) day 1 of hospitalization 47 mg/dL, 33 mg/dl (High) day 2 of hospitalization 33 mg/dL, 42 mg/dl (High) day 3 of hospitalization 42 mg/dL, 35 mg/dl (High) day 4 of hospitalization 35 mg/dL and 38 mg/dl (High) day 5 of hospitalization 38 mg/dL. On an unknown date, Body temperature: 100.6 f (High) day 2 of hospitalization 100.6 F. On an unknown date, C-reactive protein (0 mg/dl-8 mg/dl): 82 mg/dl (High) day 3 of hospitalization 82 mg/dL and 108 mg/dl (High) day 4 of hospitalization 108 mg/dL. On an unknown date, Cognitive test: normal (normal) normal. On an unknown date, Computerised tomogram head: normal (normal) Day 0 (Admission) Normal. On an unknown date, Electroencephalogram: diffuse triphasic waves, diffuse theta and delta performed 48 h after symptom onset showed diffuse triphasic waves, diffuse theta and delta slowing, and no posterior dominant rhythm. On an unknown date, Full blood count: normal (normal) day 2 of hospitalization negative. On an unknown date, Glomerular filtration rate: 6 ml/min/1.73 min (Low) day 1 of hospitalization (=60 mL/min/1.73 min), 8 ml/min/1.73 min (Low) day 2 of hospitalization (=60 mL/min/1.73 min), 7 ml/min/1.73 min (Low) day 3 of hospitalization (=60 mL/min/1.73 min), 7 ml/min/1.73 min (Low) day 4 of hospitalization (=60 mL/min/1.73 min) and 10 ml/min/1.73 min (Low) day 5 of hospitalization (=60 mL/min/1.73 min). On an unknown date, Haemoglobin (12 g/dl-16 g/dl): 13.3 g/dl (normal) day 1 of hospitalization 13.3 g/dL, 13.6 g/dl (normal) day 2 of hospitalization 13.6 g/dL, 12.5 g/dl (normal) day 3 of hospitalization 12.5 g/dL, 13.1 g/dl (normal) day 4 of hospitalization 13.1 g/dL and 12.9 g/dl (normal) day 5 of hospitalization 12.9 g/dL. On an unknown date, Hepatitis B virus test: normal (normal) Normal. On an unknown date, Inflammatory marker test: elevated (High) elevated. On an unknown date, Neurological examination: it was nonfocal Day 0 (Admission) It was nonfocal. On an unknown date, Oxygen saturation: normal (normal) Normal. On an unknown date, Physical examination: showed fluctuatingattention,disorientation it showed fluctuating attention, disorientation to  time and space, left/right confusion, and intermittently followed one-step commands. On an unknown date, Platelet count (130-400): 108 k/µl (Low) day 1 of hospitalization 108 K/µL, 115 k/µl (Low) day 2 of hospitalization 115 K/µL, 120 k/µl (Low) day 3 of hospitalization 124 K/µL, 124 k/µl (Low) day 4 of hospitalization 124 K/µL and 153 k/µl (normal) day 5 of hospitalization 153 K/µL. On an unknown date, Red blood cell sedimentation rate (0 mm/h-30 mm/h): 12 mm/h (normal) day 3 of hospitalization 12 mm/h and 110 mm/h (High) day 4 of hospitalization 110 mm/h. On an unknown date, Renal function test: was at baseline (normal) was at baseline. On an unknown date, SARS-CoV-2 RNA: negative (Negative) day 1 of hospitalization Negative and negative (Negative) day 3 of hospitalization Negative. On an unknown date, SARS-CoV-2 antibody test: positive (Positive) day 2 of hospitalization Positive. On an unknown date, Serology test: normal (normal) Normal. On an unknown date, Sputum culture: negative (Negative) day 3 of hospitalization Negative. On an unknown date, Thyroid function test: normal (normal) Normal. On an unknown date, Vitamin B12: normal (normal) Normal. On an unknown date, White blood cell count (3.5 k/µl-10 k/µl): 6.02 k/µl (normal) day 1 of hospitalization 6.02 K/µL, 5.50 k/µl (normal) day 2 of hospitalization 5.50 K/µL, 6.5 k/µl (normal) day 3 of hospitalization 6.5 K/µL, 4.88 k/µl (normal) day 4 of hospitalization 4.88 K/µL and 4.06 k/µl (normal) day 5 of hospitalization 4.06 K/µL.     The action taken with mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown) was unknown.   For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter considered ENCEPHALOPATHY (Acute transient encephalopathy/transient inflammatory encephalopathy) to be related.    Concomitant medications included anticoagulation, phosphate binder.   The patient experienced the symptoms intermittent inattention, disorientation to time and space, left/right confusion, decreased fluency, generalized weakness, and gait instability within 24 h of her first Moderna COVID-19 vaccine injection. Examination showed fluctuating attention, disorientation to time and space, left/right confusion, and intermittently followed one-step commands.  The isolated febrile episode and the strict temporal correlation between symptom onset and the Moderna COVID-19 vaccine injection, a joint decision with infectious disease team was made to defer central nervous system (CNS) antibiotic and antiviral coverage after performing a lumbar puncture and an MRI of the brain. The very strict temporal correlation between symptom onset and the Moderna COVID-19 vaccine injection, and the extensive negative work-up, it was suggested that an exaggerated immune response to mRNA vaccine in the setting of remote COVID-19 infection (1 year prior) was the most likely cause of the transient inflammatory encephalopathy without any treatment medication. This abnormal response was amplified by the patient's systemic persistent inflammation, a common feature of end-stage kidney disease and hemodialysis.  On day 5 postvaccine, day 3 of hospitalization patient's symptoms suddenly and completely resolved without any treatment medication. Patient was monitored for another day in the hospital and discharged at her baseline.  Company comment: This literature non-study case concerns a 69-year-old, female patient with multiple comorbidities including end-stage renal disease, well-controlled hypertension, and diabetes but was taking maintenance medications and undergoing regular dialysis, who was hospitalized for the unexpected acute event of Encephalopathy. The symptoms started within 24 hours after receiving the first dose of mRNA-1273 COVID-19 vaccine, initially presenting with confusion, weakness, gait instability and decreased speech. This prompted consult to the emergency department where she was observed to have fluctuating attention, disorientated to time and space, with left/right confusion and intermittently followed one-step commands. Neurologic examination was otherwise non-focal. Pulse oximetry, blood counts, serum biochemistry and head computerized tomography were all normal. Renal function and glucose tests throughout the hospital course were consistently elevated but remained within the patient's baseline values. Diffuse slowing was detected on electroencephalography, with appearance of diffuse triphasic waves and absence of posterior dominant rhythm. Maintenance medications were continued and hemodialysis was done as scheduled, while admitted. On day 2 of hospitalization (4 days post-vaccination), the patient developed low grade fever but the results of the infectious panel (complete blood count, chest X-ray, blood, sputum and Legionella cultures, and SARS-CoV-2 RNA) were all negative. Inflammatory markers (C-reactive protein and erythrocyte sedimentation rate), on the other hand, were elevated and up-trending. Given that the test results were not showing a definitive infectious cause, central nervous system antibiotic and antiviral coverage was not started and the physicians opted to schedule lumbar puncture and brain MRI first. The results of the serum biochemistry and other unspecified tests also ruled out new onset medical condition, metabolic derangements and, substance intoxication or withdrawal. On day 3 of hospitalization (5 days post-vaccination), the patient suddenly improved. Results of the brain imaging study showed no acute findings and specifically ruled out ischaemic stroke, while the lumbar puncture was deferred. She was later discharged with complete resolution of symptoms after monitoring her for another day. The patient's chronic medical conditions of ESRD, along with hypertension and diabetes, could still be considered as risk factors. The benefit-risk relationship of mRNA-1273 is not affected by this report.    Most recent FOLLOW-UP information incorporated above includes: On 02-Jun-2022: Live Follow up received by safety 02-Jun-2022 has Email with Agency and contains significant information. Reporter information, Literature information (year, volume, pages), Seriousness criteria updated to hospitalization, concomitant medication, Medical History, Lab data, Treatment drugs and Event outcome were updated.; Sender's Comments: This literature non-study case concerns a 69-year-old, female patient with multiple comorbidities including end-stage renal disease, well-controlled hypertension, and diabetes but was taking maintenance medications and undergoing regular dialysis, who was hospitalized for the unexpected acute event of Encephalopathy. The symptoms started within 24 hours after receiving the first dose of mRNA-1273 COVID-19 vaccine, initially presenting with confusion, weakness, gait instability and decreased speech. This prompted consult to the emergency department where she was observed to have fluctuating attention, disorientated to time and space, with left/right confusion and intermittently followed one-step commands. Neurologic examination was otherwise non-focal. Pulse oximetry, blood counts, serum biochemistry and head computerized tomography were all normal. Renal function and glucose tests throughout the hospital course were consistently elevated but remained within the patient's baseline values. Diffuse slowing was detected on electroencephalography, with appearance of diffuse triphasic waves and absence of posterior dominant rhythm. Maintenance medications were continued and hemodialysis was done as scheduled, while admitted. On day 2 of hospitalization (4 days post-vaccination), the patient developed low grade fever but the results of the infectious panel (complete blood count, chest X-ray, blood, sputum and Legionella cultures, and SARS-CoV-2 RNA) were all negative. Inflammatory markers (C-reactive protein and erythrocyte sedimentation rate), on the other hand, were elevated and up-trending. Given that the test results were not showing a definitive infectious cause, central nervous system antibiotic and antiviral coverage was not started and the physicians opted to schedule lumbar puncture and brain MRI first. The results of the serum biochemistry and other unspecified tests also ruled out new onset medical condition, metabolic derangements and, substance intoxication or withdrawal. On day 3 of hospitalization (5 days post-vaccination), the patient suddenly improved. Results of the brain imaging study showed no acute findings and specifically ruled out ischaemic stroke, while the lumbar puncture was deferred. She was later discharged with complete resolution of symptoms after monitoring her for another day. The patient's chronic medical conditions of ESRD, along with hypertension and diabetes, could still be considered as risk factors. The benefit-risk relationship of mRNA-1273 is not affected by this report.