evidence: - Has had an allergic reaction after a previous dose of COVID-19 vaccine or an ingredient in the COVID-19 vaccine, or has any severe, life-threatening allergies - Has had myocarditis (inflammation of the heart muscle) or pericarditis (inflammation of the lining outside of the heart) [...] - Myocarditis (inflammation of the heart muscle) or pericarditis (inflammation of the lining outside the heart) have been seen rarely after COVID-19 vaccination. This risk has been observed most commonly in males 12 through 39 years of age. The chance of this occurring is low. [...] Seek medical attention right away if the vaccinated person experiences chest pain, shortness of breath, or feelings of having a fast-beating, fluttering, or pounding heart after COVID-19 vaccination. These could be symptoms of myocarditis or pericarditis.