ABSTRACT
Kounis syndrome is an acute coronary syndrome occurring in the setting of a hypersensitivity reaction. It occurs as a consequence of mast-cell activation and degranulation causing coronary artery spasm, atherosclerotic plaque erosion, or stent thrombosis. We report the case of a man who presented to the emergency department with typical angina that started 20 minutes after coronavirus disease 2019 (COVID-19) vaccine administration. Electrocardiogram showed inferior ST-elevation myocardial infarction, and coronary angiography confirmed right coronary artery stent thrombosis. Five months before, he had an acute coronary syndrome after influenza vaccine administration. Both vaccines share a common excipient, polysorbate 80. Considering the reproducibility of the reaction and the temporal association between vaccine administration and coronary events, a hypersensitivity reaction to polysorbate 80 was admitted and the patient was instructed to further avoid drugs containing it. To our knowledge, this constitutes the first reported case of type 3 Kounis syndrome after COVID-19 vaccine administration. Kounis syndrome is an uncommon disease, often undiagnosed. Its recognition and proper management are crucial to prevent future events.