The patient was diagnosed with acute inflammatory demyelinating polyneuropathy (AIDP); This is a literature report.  A 63-year-old male patient received BNT162b2 (BNT162B2), as dose 2, single (Batch/Lot number: unknown) for covid-19 immunisation. The patient's relevant medical history and concomitant medications were not reported. Vaccination history included: Bnt162b2 (DOSE 1, SINGLE), for COVID-19 immunisation. The following information was reported: DEMYELINATING POLYNEUROPATHY (medically significant), 2 days after the suspect product(s) administration, outcome "recovered", described as "The patient was diagnosed with acute inflammatory demyelinating polyneuropathy (AIDP)". The patient is presented with acute onset of ascending numbness and paresthesia in his fingers and toes over the course of 2 weeks, associated with difficulties with fine motor movements in the hands and mild gait instability. Initial symptom onset was 2 days after administration of his second Pfizer-BioNTech COVID-19 vaccination and 23 days after first vaccination. He had no diarrheal illness or other infectious symptoms preceding symptom onset and otherwise had a mild, transient vaccine reaction. Neurologic evaluation 1 month after symptom onset revealed areflexia, distal sensory loss, positive Romberg sign, wide-based gait, and mild distal weakness. Laboratory investigation revealed an elevated sedimentation rate (ESR) and vitamin D deficiency. Cerebrospinal fluid (CSF) analysis showed positive West Nile IgG consistent with remote infection but otherwise was normal. The following laboratory results were normal or negative: SARS-CoV-2 RNA PCR, complete blood count (CBC), comprehensive metabolic profile (CMP), glycosylated hemoglobin (HgbA1c), vitamins B9 and B12, serum protein electrophoresis (SPEP), antinuclear antibody (ANA), heavy metals, porphyrins, and GM1, GQ1b, and neurofascin antibodies. Electrophysiologic studies 4 weeks after symptom onset demonstrated absent sensory responses and markedly prolonged distal latencies with decreased amplitudes and slow conduction velocities of all motor responses on nerve conduction studies (NCSs) and dispersion of compound muscle action potentials consistent with demyelinating neuropathy and normal needle electromyogram (EMG). The electrodiagnostic findings suggest marked distal demyelination and conduction block. The patient was diagnosed with AIDP and treated with intravenous immunoglobulin (IVIg) 2 g/kg divided over 4 days. Within 2 weeks, he had significant improvement in distal weakness and sensation, and by 3 months, he had recovered with only mild residual distal lower extremity paresthesia. In addition, there is no established pathophysiologic association between infection or vaccination and CIDP. However, recent studies suggested that approximately 10% of CIDP cases were associated with antecedent infectious illness and 1% with preceding vaccination. Among the CIDP cases associated with antecedent infection or vaccine, clinical presentations were more likely to be acute-onset CIDP, defined as those initially diagnosed with GBS with subsequent clinical deterioration beyond 8 weeks, and associated with cranial nerve involvement. It is imperative to remember that as with any other vaccination, any proposed association between COVID-19 vaccinations and demyelinating neuropathies cannot be considered causal because these case reports have been very few compared with the number of cases vaccinated.; Sender's Comments: A contributory role of BNT162B2 to the event acute inflammatory demyelinating polyneuropathy cannot be fully excluded based on temporal relationship and lack of reported alternative explanation at this time. Consideration should also be given to the positive West Nile IgG. Case will be reassessed if additional information becomes available.  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-202300097174 Same article/ drug and different patient/event;US-PFIZER INC-PV202300041685 Same article/ drug/event and different patient;