Probable association between mRNA COVID-19 vaccine and opsoclonus-myoclonus-ataxia syndrome.

Opsoclonus-myoclonus-ataxia syndrome (OMAS) in children is most often of paraneoplastic origin, but it can also result from infectious processes, toxic and metabolic disorders, and organic events that cause damage to the brainstem or cerebellum. Post-vaccination OMAS has also been reported. We report the case of a 15-year-old girl who developed OMAS 24 hours after her first dose of mRNA COVID-19 (BioNTech) vaccine.