Among people age 29 and under, there were 484 preliminary reports of myocarditis or pericarditis through June 11. Of these, 323 met the CDC's working case definition of the condition, and 148 were still under review.
Of the 323 cases, 309 went to the hospital and the vast majority (295) were discharged; 79% had fully recovered, while nine remained hospitalized and two were in the ICU.
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Vaccine Safety Datalink findings in 12- to 39-year-olds revealed an overall myocarditis rate of 12.6 cases per million in the 3 weeks after the second dose, though most occurred within 5 days of vaccination, Shimabukuro reported.
He concluded that overall the condition was highly treatable and most patients recovered well.
That's very different from when myocarditis is caused by a viral infection, Paul Offit, MD, of Children's Hospital Philadelphia (CHOP), told STAT News. When myocarditis is caused by coxsackie or parvovirus, for instance, "it's a serious disease, often involving ICU admission, and occasionally fatal. It can require a heart transplant. That's not this. This is often transient, lasting 2 or 3 days, and resolves on its own for the most part or can be treated with anti-inflammatories."