Clinical course and treatment of patient who received the Moderna COVID-19 vaccine. This patient had been suffering from general weakness, sore throat, and generalized skin rashes without an itch followed by a persistent fever of up to 40 °C with chills approximately two weeks after her second dose of the Moderna COVID-19 vaccine. Prednisolone 15 mg twice daily was administered, but improvement was limited. Her clinical condition improved significantly, and HsCRP decreased steadily after we switched her medication to methylprednisolone 40 mg intravenously twice a day and naproxen 250 mg twice a day. Hs-CRP, high-sensitivity C-reactive protein; WBC, white blood cells.