JAMA: THE RISK of heart inflammation after receiving doses of the Moderna or Pfizer Covid vaccines has been laid bare in a huge new study of 23 million people. Myocarditis is the name given to inflammation of the heart muscles, or “myocardium”. The condition — which typically results from viral infection — can serve to reduce the heart’s ability to pump blood and result in the development of a rapid or irregular heart rhythm. It often occurs in association with pericarditis, an inflammation of ...