As the number of people vaccinated increases, people who complain of adverse reactions continue to occur. We experienced a case characterized by low blood pressure, persistent fever, edema due to increased systemic vascular permeability, and systemic inflammation confirmed by image and laboratory examinations after ChAdOx1 coronavirus disease 2019 (COVID-19) vaccination. The diagnostic criteria for multisystem inflammatory syndrome (MIS) in adults are known as fever of 3 days or more in adults, 2 or more mucocutaneous/gastrointestinal/neurologic symptoms, elevation of inflammatory markers, and clinical/imaging diagnosis of heart failure. A 67-year-old man who was medicated for hypertension and diabetes was admitted complaining of fever, maculopapular rash, diarrhea, headache, chills, and dizziness 6 days after the first vaccination of ChAdOx1 nCoV-19 in Korea. The COVID-19 test was negative but with low blood pressure, leukocytosis, skin rash, pulmonary edema, and increased inflammation markers. His lab findings and clinical course were consistent with those of MIS after COVID-19 vaccination. He was medicated with methylprednisolone 1 mg/kg and diuretics and recovered rapidly. He was discharged after 2 weeks and confirmed cure at outpatient clinic. We report an MIS case after COVID-19 vaccination in Korea.

In patients with coronavirus disease 2019 (COVID-19), thromboembolism is a frequently reported complication. However, it is reported that the incidence of arterial occlusion is rare. We experienced a case of 70-year-old male patient who developed a complication of Right common iliac arterial occlusion while treating him for confirmed COVID-19 who did not have any risk factors, such as diabetes or smoking. As in our case, it is necessary to carefully observe whether this complication occurs while treating COVID-19 patients.

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.