diagnosed with transverse myelitis; Dose 1,2: Moderna vaccine, Dose 3-5: Pfizer vaccine; This is a literature report for the following literature source(s):   A 78-year-old female patient received BNT162b2, BNT162b2 omi ba.4-5 (BNT162B2, BNT162B2 OMI BA.4-5), in Sep2022 as dose 5 (booster), single (Batch/Lot number: unknown) for covid-19 immunisation; influenza vaccine (INFLUENZA), in Sep2022 as dose number unknown, single (Batch/Lot number: unknown). The patient's relevant medical history included: "atrial fibrillation" (unspecified if ongoing); "hypertension" (unspecified if ongoing); "hyperlipidemia" (unspecified if ongoing); "osteoporosis" (ongoing). The patient's concomitant medications were not reported. Vaccination history included: Moderna (DOSE 1, SINGLE, Batch/ Lot number not reported), administration date: Dec2020, for COVID-19 immunisation; Moderna (DOSE 2, SINGLE, Batch/ Lot number not reported), administration date: Jan2021, for COVID-19 immunisation; Bnt162b2 (DOSE 3 (BOOSTER), SINGLE, Batch/ Lot number not reported), administration date: Oct2021, for COVID-19 immunisation; Bnt162b2 (DOSE 4 (BOOSTER), SINGLE, Batch/ Lot number not reported), administration date: Apr2022, for COVID-19 immunisation. The following information was reported: INTERCHANGE OF VACCINE PRODUCTS (hospitalization, medically significant) with onset Sep2022, outcome "recovering", described as "Dose 1,2: Moderna vaccine, Dose 3-5: Pfizer vaccine"; MYELITIS TRANSVERSE (hospitalization, medically significant), 6 days after the suspect product(s) administration, outcome "recovering", described as "diagnosed with transverse myelitis". The patient underwent the following laboratory tests and procedures: Angiotensin converting enzyme normal: negative; Antinuclear antibody: within normal limits; Blood creatine phosphokinase: within normal limits; C-reactive protein: within normal limits; CSF oligoclonal band: negative; CSF test: negative; Extensor plantar response: positive; anti-AQP4: negative; negative; negative; Magnetic resonance imaging: unremarkable, notes: Brain MRI was unremarkable. Initial spinal MRI showed a non-specific, nonenhancing lesion with T2 hyperintensity at T5-6; abnormality, notes: MRI was repeated on hospital day 10 which demonstrated left parasagittal and posterior cord signal abnormality at T5-T6 with T2-hyperintensity and pathologic contrast enhancement; physical exam: diffusely decreased, notes: On physical exam of the left lower extremity, strength was 4/5 for flexion and extension of the hip and knee, sensation to light touch was diffusely decreased; Red blood cell sedimentation rate normal: within normal limits; Vitamin B12: within normal limits. Therapeutic measures were taken as a result of interchange of vaccine products, myelitis transverse.  Clinical Course: A 78-year-old patient with medical history of atrial fibrillation, hypertension, hyperlipidemia, and osteoporosis presented with left lower extremity weakness and left thigh numbness. The patient was walking when she felt lightheaded and developed left thigh tingling followed by left leg weakness. She presented the next day unable to walk independently. On physical exam of the left lower extremity, strength was 4/5 for flexion and extension of the hip and knee, sensation to light touch was diffusely decreased, and Babinski sign was positive. Laboratory workup including ESR, CRP, CK, vitamin B12, and ANA were within normal limits. Brain MRI was unremarkable. Initial spinal MRI showed a non-specific, non enhancing lesion with T2 hyperintensity at T5-6. Further serum and CSF evaluation including anti-MOG and anti-AQP4 antibodies, ACE level, and oligoclonal bands was negative. Due to progression of symptoms including urine retention, MRI was repeated on hospital day 10 which demonstrated left parasagittal and posterior cord signal abnormality at T5-T6 with T2-hyperintensity and pathologic contrast enhancement. She denied any recent infectious event or common infectious symptoms. However, she had received COVID and influenza vaccines 6 days prior to symptom onset. She was diagnosed with transverse myelitis (TM) and started on intravenous methylprednisolone 1 gram daily for 5 days with improvement in weakness and sensation. TM is a rare inflammatory demyelinating disease associated with systemic autoimmune disorders, infection, and vaccination sensation. Diagnosis is based on characteristic T2 hyperintense lesions on MRI, neurologic symptoms attributable to the lesion, evidence of inflammation such as pathologic contrast enhancement, and exclusion of spinal cord compression. TM has been documented following COVID vaccines and can present after first or subsequent doses. It is proposed that CNS demyelinating syndromes after vaccines may involve molecular mimicry or autoimmune reactions between SARS-CoV-2 spike protein antibody and human tissue. We present a case of TM after COVID and flu vaccination. The patient had previously received the Moderna (12/2020, 01/2021) and Pfizer-BioNTech (10/2021, 04/2022) COVID vaccines. She developed symptoms 6 days after receiving the bivalent Pfizer-BioNTech booster and a seasonal influenza vaccine in September 2022. Of note, initial MRI of her spinal cord lesion was non-enhancing and nonspecific. Given progression of symptoms and lack of an alternative diagnosis, repeat imaging was obtained which demonstrated an enhancing lesion consistent with TM. Parainfectious and post-vaccination myelitis often have nonspecific findings on MRI. While TM typically presents with long-segment T2 hyperintensity with enhancement, enhancement is more common in subacute stages than at initial presentation. Within the framework of high value care, repeat imaging should be considered when there is a high index of suspicion for TM. Acute TM is a rare but devastating complication of COVID infection and vaccination. The reporter stated that Patients presenting with characteristic findings should be asked about triggers including infection and vaccination, including the increasingly common combination of COVID and flu vaccination. In addition, post-vaccination TM may present with nonspecific MRI findings, and clinicians with a high index of suspicion should consider the value of reimaging for diagnosis and treatment.; Sender's Comments: Based on the information in the case report, a possible causal relationship between the events interchange of vaccine products and myelitis transverse and suspect drug BNT162b2 cannot be completely 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.