Encephalopathy; abdominal tenderness; post ictal state; COVID-19; significant lethargy; Headache; Fever; Altered mental status; This literature-non-study case was reported in a literature article and describes the occurrence of MENTAL STATUS CHANGES (Altered mental status), LETHARGY (significant lethargy), HEADACHE (Headache), PYREXIA (Fever), ENCEPHALOPATHY (Encephalopathy), ABDOMINAL TENDERNESS (abdominal tenderness), POSTICTAL STATE (post ictal state) and COVID-19 (COVID-19) in a 54-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination.   The patient's past medical history included Atrial flutter, Hypothyroidism, COVID-19 in October 2020 and Cardiac ablation. Concurrent medical conditions included Type 2 diabetes mellitus, Seizures and Traumatic brain injury. Concomitant products included VALPROATE SODIUM (VALPROATE) and CARBAMAZEPINE for Seizure.   In January 2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. In February 2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. In February 2021, the patient experienced MENTAL STATUS CHANGES (Altered mental status) (seriousness criterion hospitalization), LETHARGY (significant lethargy) (seriousness criterion hospitalization), HEADACHE (Headache) (seriousness criterion hospitalization) and PYREXIA (Fever) (seriousness criterion hospitalization). On an unknown date, the patient experienced ENCEPHALOPATHY (Encephalopathy) (seriousness criteria hospitalization and medically significant), ABDOMINAL TENDERNESS (abdominal tenderness) (seriousness criterion hospitalization), POSTICTAL STATE (post ictal state) (seriousness criterion hospitalization) and COVID-19 (COVID-19) (seriousness criterion hospitalization). The patient was hospitalized for 2 days due to MENTAL STATUS CHANGES. The patient was treated with CEFTRIAXONE (intravenous) for Meningoencephalitis, at an unspecified dose and frequency; VANCOMYCIN (intravenous) for Meningoencephalitis, at an unspecified dose and frequency; ACYCLOVIR [ACICLOVIR] (intravenous) for Meningoencephalitis, at an unspecified dose and frequency; DEXAMETHASONE (intravenous) for Meningoencephalitis, at an unspecified dose and frequency and WARFARIN at an unspecified dose and frequency. At the time of the report, MENTAL STATUS CHANGES (Altered mental status), LETHARGY (significant lethargy), HEADACHE (Headache), PYREXIA (Fever), ENCEPHALOPATHY (Encephalopathy) and POSTICTAL STATE (post ictal state) had resolved and ABDOMINAL TENDERNESS (abdominal tenderness) and COVID-19 (COVID-19) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Anticonvulsant drug level: normal (normal) Valproate and carbamazepine normal. On an unknown date, Blood creatine phosphokinase: 1025 u/l (High) elevated creatine kinase of 1025 U/L. On an unknown date, Blood electrolytes: normal (normal) normal. On an unknown date, Blood glucose: normal (normal) normal. On an unknown date, Blood pressure measurement: 145/71 mmhg 145/71 mmHg. On an unknown date, Blood thyroid stimulating hormone (0.27-4.2): 4.81 µ/ml 4.81 µ/mL. On an unknown date, Body temperature: 103°f 103°F and 104.8°f The patient had a maximum documented temperature of 104.8°F axillary during his inpatient stay and fever lasted for approximately up to 30 hours after vaccination.. On an unknown date, C-reactive protein: 157.4 mg/l (High) elevated C reactive protein of 157.4. On an unknown date, Chest X-ray: normal (normal) Normal. On an unknown date, Computerised tomogram head: no acute changes showed no acute changes to suggest infarct or hemorrhage.  Postsurgical changes involving right frontoparietal calvarium, encephalomalacia right frontoparietal temporal region and to a lesser extent left parietal region similar when compared with prior CT examinations.. On an unknown date, Electrocardiogram: normal showed normal sinus rhythm with no other acute changes.. On an unknown date, Haemoglobin: 109 g/l 109 g/L. On an unknown date, Heart rate: 114/min 114/min. On an unknown date, International normalised ratio: 3.4 International Normalized Ratio (INR) of 3.4 (patient taking warfarin).. On an unknown date, Neurological examination: abnormal (abnormal) residual left-sided weakness and cognitive deficit from his traumatic brain injury. On an unknown date, Oxygen saturation: normal (normal) normal oxygen saturation on room air. On an unknown date, Platelet count: normal (normal) normal. On an unknown date, Procalcitonin: normal (normal) normal. On an unknown date, Prothrombin time (10.5-13): 37.7 sec 37.7 Sec. On an unknown date, Red blood cell sedimentation rate: 48 mm/hour 48 mm/hour. On an unknown date, SARS-CoV-2 test: positive (Positive) Four months prior to this admission, the patient had a positive-COVID- 19 PCR during a preprocedure screen before ablation of atrial flutter.. On an unknown date, Urine analysis: normal (normal) Normal. On an unknown date, White blood cell count: 12.1×10?/l 12.1×10?/L.     For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter considered MENTAL STATUS CHANGES (Altered mental status), LETHARGY (significant lethargy), HEADACHE (Headache), PYREXIA (Fever), ENCEPHALOPATHY (Encephalopathy), ABDOMINAL TENDERNESS (abdominal tenderness), POSTICTAL STATE (post ictal state) and COVID-19 (COVID-19) to be possibly related.    The patient received his first dose of mRNA-1273 COVID-19 vaccine in January 2021 which was 3 months after his minimally symptomatic COVID-19 infection. His second dose of vaccine was given in February 2021. He complained of headache a few hours following his second dose but was otherwise at baseline. The next morning his caretaker found him difficult to arouse and feverish.   There were postsurgical changes involving right frontoparietal calvarium, encephalomalacia right frontoparietal temporal region and to a lesser extent left parietal region similar when compared with prior CT examinations.  Patient had an unwitnessed seizure and postictal confusion secondary to fever. Absence of new focal neurological deficits and the CT findings rule out cerebrovascular accident.  Meningoencephalitis was considered but lumbar puncture could not be done due to supratherapeutic INR secondary to warfarin. With the improvement in mental status and resolution of fever, infectious aetiology was deemed unlikely  The patient received supportive treatment with intravenous fluids and antipyretics.  He was therefore started on empiric treatment for meningoencephalitis with intravenous ceftriaxone,  vancomycin, acyclovir and dexamethasone but these were discontinued after patient's mental status markedly improved overnight.  He was discharged after his mental status returned to baseline.  Meningoencephalitis was initially suspected but treatment was discontinued after mental status changes improvement overnight and was discharges 2 days after admission.; Sender's Comments: This case concerns a 54-year-old, male with a history of assisted care living, seizures under treatment with valproic and carbamazepine, traumatic brain injury as well as postsurgical changes on computerized tomography of the head, atrial flutter, type 2 diabetes and hypothyroidism, who experienced the unexpected serious (as per hospitalization) events of mental status changes, lethargy, headache, pyrexia and abdominal tenderness. The differential diagnosis captured as events were encephalopathy and postictal state. Patient´s COVID 19 PCR test was positive with no clear interpretation. However, this happened less than 15 days after the second dose administration (no LoE). The event occurred approximately 1 days after the second dose of mRNA-1273 Moderna vaccine. The rechallenge not applicable because no other dose is expected.  The medical history of Traumatic Brain injury and previous structural lesions to frontoparietal lobes, seizures under treatment with Valproic and Carbamazepin, with no EEG or ammonium level reported, are strong confounders and co suspect drugs. The benefit-risk relationship of mRNA-1273 Moderna vaccine in not affected by this report