While some young adults have been hospitalized with vaccine-related myocarditis, most cases resolve on their own, and there have been no deaths linked to the vaccine.
One developed acute encephalopathy, which effects brain function, while the other developed acute myocarditis, which is the inflammation of the heart muscle.
And there were no cases of myocarditis or pericarditis—inflammation of the heart muscle or lining—which have occurred in a small percentage of teens and young adults who got the Pfizer or Moderna vaccines.