Adult-Onset Still’s Disease after COVID-19 Vaccination: A Case Report and Review

To overcome the global pandemic of coronavirus disease 2019 (COVID-19), COVID-19 vaccination has been developed and distributed. Many people have received the vaccination worldwide. However, there are some vaccinated individuals who complain of side effects due to COVID-19 vaccination. We report the case of a patient who developed adult-onset Still’s disease (AOSD) after receiving the messenger RNA COVID-19 vaccine. A 21-year-old male patient without a previous medical history developed a fever on the day of the first dose of the vaccine. He had persistent fever, arthralgia of the knee and wrist, hyperferritinemia, transient skin rash, and negative test results for rheumatoid factor or antinuclear antibody. Positron emission tomography-computed tomography scan showed lymphadenopathies with reactive patterns and no malignancy. His symptoms and laboratory abnormalities gradually improved with glucocorticoid, cyclosporine, methotrexate, and tocilizumab treatment. Although its causality is still not confirmed, AOSD should be considered in a case that meets the diagnostic criteria after COVID-19 vaccination.