The vaccines have been studied and are safe and effective. The benefits of receiving either of the mRNA vaccines far outweigh the risk of a rare occurrence of myocarditis, an inflammation of the heart muscle, and pericarditis, an inflammation of the outer lining of the heart. In both cases, the body’s immune system causes inflammation in response to an infection or some other trigger. Also, most patients with myocarditis and pericarditis who received care responded well to treatment and rest and quickly felt better. The risk of developing myocarditis or pericarditis is much greater after a COVID-19 infection than after vaccination. More info about risks and benefits here.