CIDP exacerbation following COVID-19 vaccination; CIDP exacerbation following COVID-19 vaccination; This is a literature report.  A 54-year-old male patient received BNT162b2, BNT162b2 omi ba.4-5 (BNT162B2, BNT162B2 OMI BA.4-5), as dose 3 (booster), single (Batch/Lot number: unknown) for covid-19 immunisation. The patient's relevant medical history included: "urinary tract infection" (unspecified if ongoing); "obsessive-compulsive disorder." (unspecified if ongoing); "depression" (unspecified if ongoing); "chronic sacral ulcer" (unspecified if ongoing); "Suprapubic catheter" (unspecified if ongoing); "neurogenic bladder" (unspecified if ongoing); "spina bifida" (unspecified if ongoing), notes: myelomeningocele; "hydrocephalus" (unspecified if ongoing); "Arnold Chiari syndrome type 2" (unspecified if ongoing); "CIDP" (unspecified if ongoing); "wheelchair bound" (unspecified if ongoing); "non invasive mechanical ventilation" (unspecified if ongoing); "Hospitalisation" (unspecified if ongoing). The patient's concomitant medications were not reported. Vaccination history included: Bnt162b2 (DOSE 1,SINGLE), for COVID-19 immunisation; Bnt162b2 (DOSE 2, SINGLE), for COVID-19 immunisation; Bnt162b2 (DOSE 3 (BOOSTER), SINGLE), for COVID-19 immunisation, reaction(s): "CIDP". The following information was reported: CHRONIC INFLAMMATORY DEMYELINATING POLYRADICULONEUROPATHY (hospitalization, medically significant, life threatening), CONDITION AGGRAVATED (hospitalization, medically significant, life threatening), all with latency 3 days after the suspect product(s) administration, outcome "unknown" and all described as "CIDP exacerbation following COVID-19 vaccination". The patient underwent the following laboratory tests and procedures: Alanine aminotransferase: 154; Aspartate aminotransferase: 160; Blood alkaline phosphatase: 353; Blood gases: unknown results; Blood pressure measurement: within normal limits; 105/55; Computerised tomogram: no evidence of intracranial hemorrhage, territoria, notes: infarct or mass effect, chronic findings of Arnold Chiari malformation type 2 were seen, which were unchanged from the previous scan; revealed bilateral dependent lung, notes: dense consolidations and additional scattered patchy ground glass and consolidative opacities suspicious for aspiration pneumonia and osteomyelitis of the right ischial tuberosity underlying chronic sacral decubitus ulcer; Computerised tomogram abdomen: revealed bilateral dependent lung, notes: dense consolidations and additional scattered patchy ground glass and consolidative opacities suspicious for aspiration pneumonia and osteomyelitis of the right ischial tuberosity underlying chronic sacral decubitus ulcer; Computerised tomogram thorax: revealed bilateral dependent lung, notes: dense consolidations and additional scattered patchy ground glass and consolidative opacities suspicious for aspiration pneumonia and osteomyelitis of the right ischial tuberosity underlying chronic sacral decubitus ulcer; Full blood count: normal; Heart rate: within normal limits; 154, notes: Units: beats per minute; Electrodiagnostic: were consistent with severe multifocall, notes: with no signs to suggest superimposed myopathic polyneuropathy; 15 cm of water; 76 cm of water; Liver function test: normal; Magnetic resonance imaging: no acute changes; Metabolic function test: normal; Nerve conduction studies: were consistent with severe multifocal, notes: demyelinating motor polyneuropathy with no signs to suggest superimposed myopathic polyneuropathy; Neurological examination: improved; Oxygen saturation: within normal limits; 88 %; PCO2: 39; 53; pH body fluid: 7.49; 7.37; PO2: 79; 309; Polymerase chain reaction: negative; Respiratory rate: 16; Urine analysis: positive, notes: leukocyte esterase and moderate amount of bacteria. Therapeutic measures were taken as a result of chronic inflammatory demyelinating polyradiculoneuropathy, condition aggravated.; Sender's Comments: A possibly contributory role of BNT162B2, BNT162B2 OMI BA.4-5 in triggering the onset of CIDP exacerbation might not be fully excluded, considering the temporal relationship.  More immunological and biomolecular evidence would be needed to explore the plausible physiopathologic mechanism between the vaccination and the event occurrence.  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,Linked Report(s) : US-PFIZER INC-PV202300100633 Same article/patient/drug/event and different dose.;