Rare Heart Risk From Covid mRNA Vaccines Tracked in New Study

A rapid, two-step immune reaction may underlie rare cases of heart inflammation seen after Covid mRNA vaccination, Stanford University researchers found, shedding light on a mechanism that’s fueled scientific debate and political controversy since the pandemic.

The condition, myocarditis, appears most often in adolescent males and young men. It typically begins one to three days after a second vaccine dose, bringing on chest pain, shortness of breath or palpitations. Symptoms usually resolve quickly with supportive care — monitoring, rest and basic treatment to ease inflammation while the heart recovers on its own.

The new research, published Wednesday in Science Translational ...