A case of encephalitis following COVID-19 vaccine.

We describe the first case of encephalitis following coronavirus disease 2019 (COVID-19) vaccination. Our patient was a 46-year-old Japanese woman who presented with acute onset diplopia. Subsequent magnetic resonance imaging revealed brain stem encephalitis that was rapidly responsive to high dosage steroid therapy and completely improved. Although the occurrence of encephalitis after vaccination could have just been a casual temporal association, her symptoms were temporally correlated with two vaccinations. Our case suggests caution and indicates treatment and prognosis, despite no evidence of a causal relationship. Nonetheless, this report emphasizes the enormous benefits of vaccination, which should not be undermined.