Confusion; severe encephalopathy; dizziness; Double vision; bilateral upper extremity myoclonus; Sweet syndrome; orofacial movements; Headache; acute aseptic meningoencephalitis; This literature-non-study case was reported in a literature article and describes the occurrence of ENCEPHALITIS (acute aseptic meningoencephalitis), CONFUSIONAL STATE (Confusion), ENCEPHALOPATHY (severe encephalopathy), DIZZINESS (dizziness), DIPLOPIA (Double vision), MYOCLONUS (bilateral upper extremity myoclonus), ACUTE FEBRILE NEUTROPHILIC DERMATOSIS (Sweet syndrome), DYSKINESIA (orofacial movements) and HEADACHE (Headache) in a 77-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination.   LITERATURE REFERENCE: et al.. Acute encephalitis, myoclonus and Sweet syndrome after mRNA-1273 vaccine. BMJ Case Rep. 2021;14(7):e243173     Concurrent medical conditions included Coronary artery disease, Hyperlipidaemia and Hypothyroidism.    On an unknown date, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On an unknown date, the patient experienced ENCEPHALITIS (acute aseptic meningoencephalitis) (seriousness criterion medically significant), CONFUSIONAL STATE (Confusion) (seriousness criterion hospitalization), DIZZINESS (dizziness) (seriousness criterion hospitalization), DIPLOPIA (Double vision) (seriousness criterion hospitalization), MYOCLONUS (bilateral upper extremity myoclonus) (seriousness criterion hospitalization), ACUTE FEBRILE NEUTROPHILIC DERMATOSIS (Sweet syndrome) (seriousness criterion hospitalization), DYSKINESIA (orofacial movements) (seriousness criterion hospitalization) and HEADACHE (Headache) (seriousness criterion hospitalization). an unknown date, the patient experienced ENCEPHALOPATHY (severe encephalopathy) (seriousness criteria hospitalization and medically significant). The patient was treated with METHYLPREDNISOLONE for Inflammatory reaction, at a dose of 1 g once a day; PREDNISONE for Sweet's syndrome, at a dose of 60 mg once a day; VANCOMYCIN for Sepsis and Meningitis, at an unspecified dose and frequency; CEFEPIME for Sepsis and Meningitis, at an unspecified dose and frequency; CEFTRIAXONE for Sepsis and Meningitis, at an unspecified dose and frequency; AMPICILLIN for Sepsis and Meningitis, at an unspecified dose and frequency; DOXYCYCLINE for Sepsis and Meningitis, at an unspecified dose and frequency and ACYCLOVIR [ACICLOVIR] for Sepsis and Meningitis, at an unspecified dose and frequency. At the time of the report, ENCEPHALITIS (acute aseptic meningoencephalitis), CONFUSIONAL STATE (Confusion), ENCEPHALOPATHY (severe encephalopathy), DIZZINESS (dizziness), DIPLOPIA (Double vision), MYOCLONUS (bilateral upper extremity myoclonus), ACUTE FEBRILE NEUTROPHILIC DERMATOSIS (Sweet syndrome), DYSKINESIA (orofacial movements) and HEADACHE (Headache) had resolved.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): In 2021, Alanine aminotransferase (6-55): 93 (High) 93 U/L. In 2021, Aldolase: 15.8 u/l (High) reference value <8.1. In 2021, Antineutrophil cytoplasmic antibody: negative (Negative) negative. In 2021, Antinuclear antibody: positive (1:160) (Positive) Positive (1:160) and negative (Negative) Negative. In 2021, Aspartate aminotransferase (5-34): 67 u/l (High) 67  U/L. In 2021, Blood creatine phosphokinase (29-200): 1200 u/l, (High) 1200 U/L. In 2021, Blood culture: unremarkable (Negative) Unremarkable. In 2021, Blood glucose (40-70): 65 mg/dl (normal) 65 mg/dl. In 2021, Blood immunoglobulin G: increased (High) increased (CSF + blood). In 2021, Blood lactic acid (0.5-2.2): 0.67 mmol/l (normal) 0.67 mmol/L. In 2021, Blood smear test: unrevealing (Negative) Unrevealing. In 2021, Blood thyroid stimulating hormone (0.350-4.940): 0.153 (Low) 0.153 micro international unit per millilitre. In 2021, C-reactive protein (0.00-0.50): 139 mg/dl (High) 139 mg/dl. In 2021, CSF culture: negative (Negative) Negative. In 2021, Cardiolipin antibody: igg, igm negative (Negative) IgG, IgM Negative. In 2021, Complement factor C3 (82-193): 108 mg/dl (normal) 108 mg/dl. In 2021, Complement factor C4 (15-57): 41 mg/dl (normal) 41 mg/dl. In 2021, Computerised tomogram abdomen: unrevealing (Negative) Unrevealing. In 2021, Computerised tomogram pelvis: unrevealing (Negative) Unrevealing. In 2021, Computerised tomogram thorax: unrevealing (Negative) Unrevealing. In 2021, Cryptococcus test: negative (Negative) Negative. In 2021, Culture urine: unremarkable (Negative) Unremarkable. In 2021, Dermatologic examination: deep red, non- scaly, oedematous papules (abnormal) deep red, non- scaly, oedematous papules coalescing into plaques on the abdomen, upper chest, proximal upper extremities, bilateral upper flanks and back, with scattered non- follicular pustules. In 2021, Double stranded DNA antibody: negative (Negative) Negative. In 2021, Electroencephalogram: abnormal (abnormal) Revealed a generalised slow background in the theta range, with state changes and  reactivity but no sleep features. Facial and upper limb movements were captured on video recording without  an epileptiform correlate on electroencephalogram.. In 2021, Electrophoresis protein: unrevealing (Negative) Unrevealing. In 2021, Flow cytometry: unrevealing (Negative) Unrevealing. In 2021, Fungal test: negative (Negative) negative, No fungi seen. In 2021, Gram stain: negative (Negative) Negative, No organisms seen. In 2021, Histology: oedematous papillary dermis (abnormal) oedematous papillary dermis and a band- like infiltrate of predominantly neutrophils and histiocytoid cells  with nuclear debris in the superficial dermis without vasculitic changes. In 2021, Immunology test: normal (normal) Normal. In 2021, Magnetic resonance imaging: unremarkable (Negative) Unremarkable. In 2021, Mycobacterium test: negative (Negative) No acid- fast bacilli seen. In 2021, Neurological examination: orofacial movements and bilateral upper extremity (abnormal) intermittent and irregular orofacial movements and bilateral upper extremity myoclonus. In 2021, Neutrophil count (1.78-5.38): 15.5 x 10^9/l (High) 15.5 x 10^9/L. In 2021, Procalcitonin: 0.35 ng/ml, (High) reference value <0.05. In 2021, Protein total (15-45): 65 mg/dl (High) 65 mg/dl. In 2021, Pyrexia: high (High) High (>38°C). In 2021, Rheumatoid factor: positive (1:2) (Positive) Positive (1:2). In 2021, SARS-CoV-2 test: negative (Negative) negative, making it unlikely that this was a virus- mediated inflammatory response. In 2021, Serum ferritin (5-275): 396.70 (High) 396.70, mg/dL. In 2021, Treponema test: negative (Negative) Negative and non-reactive (Negative) Non-reactive. In 2021, Viral test: negative (Negative) Not detected - Human metapneumovirus, parainfluenza virus 14, rhinovirus, SARS- CoV-2, influenza A, influenza B, RSV, adenovirus, Bordetella  pertussis, Chlamydophila pneumoniae, Mycoplasma pneumoniae,  coronavirus 229E, coronavirus HKU1, coronavirus NL63,  coronavirus OC43. In 2021, White blood cell count (3.5-10.5): 18.5 x 10^9/l (High) 18.5 x 10^9/L and 120 10^6/l (High) reference value =5.     The action taken with mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) was unknown.   For mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular), the reporter considered ENCEPHALITIS (acute aseptic meningoencephalitis), CONFUSIONAL STATE (Confusion), ENCEPHALOPATHY (severe encephalopathy), DIZZINESS (dizziness), DIPLOPIA (Double vision), MYOCLONUS (bilateral upper extremity myoclonus), ACUTE FEBRILE NEUTROPHILIC DERMATOSIS (Sweet syndrome), DYSKINESIA (orofacial movements) and HEADACHE (Headache) to be possibly related.    Concomitant medications were not provided by the reporter.   Fever started 1 day after vaccine administration and was episodic, lasting for minutes to hours and recurring throughout the day. Over the next 48 hours, the patient developed a generalized body rash, starting from the trunk and spreading to the extremities. Thereafter, he began to experience headache, dizziness and double vision, which later progressed gradually to severe encephalopathy in the course of 5 days. On dermatological examination, he was noted to have deep red, non-scaly, oedematous papules coalescing into plaques on the abdomen, upper chest, proximal upper extremities, bilateral upper flanks and back, with scattered non-follicular pustules. On neurological examination, he had intermittent and irregular orofacial movements and bilateral upper extremity myoclonus.  The patients HIV-1 was non- reactive. The patient was also evaluated for Lyme disease, Rickettsia and Typhus on basis of IgG/IgM titers showing negative results. Other antibody test included were Smith, Ro, La and, Anti Jo-1 IgG and all were negative. Autoimmune encephalitis panel result: ANNA 1 (Hu), ANNA 2 (Ri), ANNA 3, PCA1 (Yo), PCA2, PCA- Tr (DNER), AGNA/SOX1, amphiphysin, CRMP5/CV2, GAD65, Ma2/Ta, Myelin Ab, aquaporin 4, NMDAR1, AMPAR1, AMPAR2, GABABR, LGI1, CASPR2, DPPX Rec, VGKC all were negative.  Evaluation for malignancy was unrevealing, including serum protein electrophoresis, peripheral blood smear, peripheral blood flow cytometry, and CT of chest, abdomen and pelvis.  Treatment was not provided for rest of the events.  Company Comment: 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.   Most recent FOLLOW-UP information incorporated above includes: On 04-Aug-2021: Full text article received.; 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.