Acute disseminated encephalomyelitis; This is a literature report.  A 61-year-old female patient received BNT162b2 (BNT162B2), as dose 1, single (Batch/Lot number: unknown) for covid-19 immunisation. The patient's relevant medical history included: "hypertension" (unspecified if ongoing); "anxiety" (unspecified if ongoing); "generalized weakness" (unspecified if ongoing), notes: progressively worsening over the past 6 to 8 weeks; "altered mental status" (unspecified if ongoing), notes: progressively worsening over the past 6 to 8 weeks; "change in the patient speech" (unspecified if ongoing); "difficulty communicating" (unspecified if ongoing). The patient's concomitant medications were not reported. The following information was reported: ACUTE DISSEMINATED ENCEPHALOMYELITIS (medically significant, life threatening), outcome "recovering". The event "acute disseminated encephalomyelitis" required emergency room visit. The patient underwent the following laboratory tests and procedures: Angiogram: did not show any acute pathology.; Antibody test: Negative, notes: for Ehrlichia chaffeensis, Anaplasma phagocytophilum, Babesia microti, and Lyme disease; Negative; Negative; Negative; Negative; Negative; Antineutrophil cytoplasmic antibody: Negative; Negative; Negative; Antinuclear antibody: within normal limits; Bacterial test: Not detected; Not detected; Blood bicarbonate: 11 mmol/L; Blood chloride: 120 mmol/L; Blood cortisol: within normal limits; Blood culture: Negative; Blood glucose: within normal limits; Blood immunoglobulin G: Negative; Blood immunoglobulin G: 4.0 mg/dl, notes: in the CSF; Negative; Blood potassium: 3.2 mmol/L; Blood pressure measurement: 183/113, notes: hypertensive; Blood test: Negative, notes: negative for human polyomavirus 2, myeloperoxidase antibodies, serine protease 3 antibodies, contactin-associated protein-2 IgG antibody, leucine-rich glioma inactivated 1 protein IgG antibody, and myelin oligodendrocyte glycoprotein antibody; Computerised tomogram abdomen: did not show any acute pathology.; Computerised tomogram pelvis: did not show any acute pathology.; Cryptococcus test: Not detected; CSF cell count: unremarkable, notes: cerebrospinal fluid analysis; CSF culture: unremarkable, notes: cerebrospinal fluid analysis; CSF glucose: unremarkable, notes: cerebrospinal fluid analysis; CSF oligoclonal band: Negative, notes: A multiple sclerosis panel was obtained which was negative for oligoclonal bands in the CSF; CSF protein: 61 mg/dl, notes: cerebrospinal fluid analysis; CSF test: unremarkable, notes: for human polyomavirus 2, and 14-3-3 Protein Tau; CSF white blood cell differential: unremarkable, notes: cerebrospinal fluid analysis; Culture: did grow Klebsiella oxytoca; Cytomegalovirus test: Not detected; Electroencephalogram: nonspecific diffuse cerebral dysfunction, notes: which is nonspecific without evidence of seizures or epileptiform discharges; Enterovirus test: Not detected; Haemoglobin: 12.6 g/dl; Herpes simplex test: Not detected; Not detected; Herpes virus test: Not detected; Influenza virus test: Not detected; Magnetic resonance imaging: acute disseminated encephalomyelitis.; did not show any further progression of her disease, notes: process. performed 1 month later; Nasopharyngeal swab: within normal limits; Neisseria test: Not detected; PCO2: less than 10, notes: Arterial blood gas showed; pH body fluid: 7.65, notes: Arterial blood gas showed; PO2: 124, notes: Arterial blood gas showed; Polyomavirus test: Negative; Negative; Procalcitonin: within normal limits; Respiratory rate: 30s; Staphylococcus test: Negative; Streptococcus test: Not detected; Not detected; Thyroid function test: within normal limits; Toxicologic test: Positive, notes: for tetrahydrocannabinol; Urine analysis: unremarkable; Varicella virus test: Not detected; Viral test: Not detected; White blood cell count: 10.1, notes: K/uL. Therapeutic measures taken as a result of acute disseminated encephalomyelitis included treatment with 5 doses of methylprednisolone 1 g and intravenous immunoglobulin (IVIG) 2 g/kg over 5 days.   No follow-up attempts are possible. No further information is expected.; Sender's Comments: Based on the current available limited information in the case provided, the causal association between the events and the use of suspect product BNT162B2 cannot be fully excluded.  The impact of this report on the benefit/risk profile of the Pfizer product is evaluated as part of Pfizer procedures for safety evaluation, including the review and analysis of aggregate data for adverse events. Any safety concern identified as part of this review, as well as any appropriate action in response, will be promptly notified to regulatory authorities, Ethics Committees, and Investigators, as appropriate.