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An event is serious (based on the ICH definition) when the patient outcome is:

  • * death

  • * life-threatening

  • * hospitalisation

  • * disability

  • * congenital anomaly

  • * other medically important event

A 45-year-old man developed acute disseminated encephalomyelitis (ADEM) anti-myelin oligodendrocyte glycoprotein (MOG) antibody-positive following administration of AZD-1222 for immunisation against COVID-19.

The man received first dose of AZD-1222 [ChAdOx1-S nCoV-19 vaccine, Oxford-AstraZeneca; dosage and route not stated] for immunisation against COVID-19 on 25 February 2021. His history included isolated episode of objective vertigo lasting for several hours (in December 2019) and allergic asthma triggered by pollen, which was well controlled by inhaled unspecified corticosteroids with short acting beta 2 agonist drugs. He did not have familiar and personal history for neurological diseases. Within 12h after vaccination, he experienced fever associated with diffuse myalgia up to 36h. On 4 March 2021, he experienced burning feeling on the back followed in a couple of hours by backpain. He also experienced increased in intensity with a sensation of numbness and hypoesthesia symmetrically involving thighs, knees and perineum. On 5 March 2021, he was hospitalised for urinary retention

The man was treated with tamsulosin. On 7 March 2021, his clinical status deteriorated with a loss of feet's vibration sensation accompanied by gait difficulties and febrile status and he was transferred to emergency department. An urological examination showed urinary retention and neurological examination revealed an alteration of sensibility on abdominal region associated with diffused myalgia. He was discharged after performing cranial-CT. On 9 March 2021, he was hospitalised to neurological department due to gait disorder worsening. Upon examination, he was afebrile, saturating well on room air, his BP was 120/50mm Hg and HR was 80/min. A neurological examination revealed paresis of the lower limbs, reflexes were present and symmetric with a prevalence of left Achillei. The urinary retention and hypoesthesia or hypopallestesia up to D5 were seen. His laboratory testing showed neutrophile-dominant leukocytosis at 80.7% and mild increase of CRP.

A serological panel was negative. An IgG positivity found for EBV nuclear antigen, herpes simplex1, HHV6, adenovirus, and cytomegalovirus, Epstein-Barr virus (EBV) viral capsid antigen, parvovirus B19, varicella-zoster virus and toxoplasma. A spinal cord MRI showed a central non expansive short tau iversion recovery (STIR) signal lesions extended to spinal cord from D10 until conus with no enhancement after administration of gadolinium. The cerebrospinal fluid revealed 43 cells associated with mild hyperproteinorachia and normal glycorrhachia and oligoclonal bands. He was treated with empirical ceftriaxone in the context of an infectious myelitis and and later with piperacillin/tazobactam. Later, PCR and cultural CSF microbiological panel were negative, hence piperacillin/tazobactam was discontinued. His autoimmune screening was normal, acquaporin-4 antibodies and anti-SARS-CoV2 IgG and IgM were negative. He was anti-MOG positive. Thereafter, he was treated with methylprednisolone. After 4 days, he showed improvement on sensibility gait symptoms but still had bladder dysfunction. He was previously misdiagnosed with AZD-1222 vaccine related transverse myelitis. Therefore, on 13 March 2021, a brain MRI was performed and showed multiple poorly defined margins hyperintense T2-weighted and fluid-attenuated inversion recovery (FLAIR) bilateral subcortical/cortical gray-white matter lesions, and a frontal venous malformation. The spinal cord involvement was stable, normal ECG and none of the brain and spinal lesions revealed gadolinium-enhancement. After 3 months, the follow-up brain MRI revealed resolution of a monophasic demyelinating event previously seen on initial presentation. His spinal cord status was also improved, stable anti-MOG titer with disappearance of the hyperintense streak in STIR with concomitant clinical resolution of neurological deficits except for urinary retention that was persisting. Based on findings, he was diagnosed with ADEM which was considered related to​ AZD-1222.