Abstract
RATIONALE: In 2022, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron spread widely around the world. In the context of most literature reporting weakened virulence of the virus, immunocompromised patients who have not been vaccinated should be vigilant for the development of encephalitis following SARS-CoV-2 infection. PATIENT CONCERNS: A 58-year-old male patient with immunodeficiency presented with respiratory and psychiatric symptoms after contracting SARS-CoV-2 Omicron variant. DIAGNOSES: The patient was diagnosed with coronavirus disease 2019 infection and associated acute primary encephalitis. INTERVENTIONS: The patient was received comprehensive treatment including Azvudine antiviral therapy, immunoglobulin infusion, and methylprednisolone anti-inflammatory therapy. OUTCOMES: The patient's condition improved and he was discharged smoothly. One month after discharge, the patient returned for follow-up, and the occipital lobe still had a few slow waves on electroencephalogram, but the patient reported no seizure events since discharge. LESSONS: During the prevalence of the SARS-CoV-2 Omicron variant, we believe that it is still necessary to be vigilant about immunocompromised patients developing encephalitis. Early use of cranial magnetic resonance imaging as a diagnostic assistance is conducive to early diagnosis and treatment of patients.