Here are four key takeaways from the group’s analysis:
1. 82% of vaccine-related cases of myocarditis occurred after the second dose of vaccine
Also, the team added, the median time from vaccination to onset of symptoms was three days associated with the first dose but two days associated with the second dose. Almost three out of four cases occurred within seven days of vaccination.
2. Young men are at greatest risk
Vaccine-related myocarditis is most common in younger patients, with 73% occurring in patients younger than 30 years and 33% in patients younger than 18 years. In addition, 82% of the patients were men.
3. There are some important differences between vaccine-related myocarditis and other cases of myocarditis
Vaccine-related cases, for example, appear to lead to the onset of symptoms more quickly than typical cases.
“Cases of myocarditis reported after COVID-19 vaccination were typically diagnosed within days of vaccination, while cases of typical viral myocarditis can often have sluggish courses with symptoms sometimes present for weeks to months after a trigger if the cause is ever identified,” the authors wrote.
Also, the “key symptoms” associated with myocarditis resolve more rapidly in vaccine-related cases than in typical cases.
“Although nearly all individuals with cases of myocarditis were hospitalized and clinically monitored, they typically experienced symptomatic recovery after receiving only pain management,” the authors wrote. “In contrast, typical viral cases of myocarditis can have a more variable clinical course. For example, up to 6% of typical cases of adolescent viral myocarditis require a heart transplant or result in death.”
4. We need more data
Data on long-term outcomes, the authors noted, are still unavailable. The CDC is actively working to get additional information about previous cases, but such reporting will take time.
The full JAMA study is available here.