The CDC reports its Advisory Committee on Immunization Practices (ACIP) COVID-19 Vaccine Safety Technical (VaST) Work Group has reports myocarditis, an inflammation of the heart muscle, in some vaccinated individuals.
Per the VaST such cases seem to occur:
- predominantly in adolescents and young adults,
- more often in males than females,
- more often following dose 2 than dose 1, and
- typically within 4 days after vaccination.
VaST reports there are “relatively few reports of myocarditis to date” but didn’t specify how many in its May 17 statement.
Most cases appear to be mild, and follow-up of cases is ongoing.
Within CDC safety monitoring systems, rates of myocarditis reports in the window following COVID-19 vaccination have not differed from expected baseline rates. However, VaST members felt that information about reports of myocarditis should be communicated to providers.
According to the Mayo Clinic, myocarditis can affect the heart muscle and its electrical system, reducing a heart’s ability to pump and causing rapid or abnormal heart rhythms (arrhythmias). Mild cases may present asymptomatic or with chest pain or shortness of breath. In serious cases, the signs and symptoms of myocarditis vary, depending on the cause of the disease.
Per Mayo Clinic, common myocarditis signs and symptoms include:
- Chest pain
- Rapid or abnormal heart rhythms (arrhythmias)
- Shortness of breath, at rest or during physical activity
- Fluid retention with swelling of your legs, ankles and feet
- Fatigue
- Other signs and symptoms of a viral infection, such as a headache, body aches, joint pain, fever, a sore throat or diarrhea
When children develop myocarditis, they might have signs and symptoms including:
- Fever
- Fainting
- Breathing difficulties
- Rapid breathing
- Rapid or abnormal heart rhythms (arrhythmias)
Mayo Clinic suggests contacting a doctor if you have symptoms of myocarditis, particularly chest pain and shortness of breath. If you have severe symptoms, go to the emergency room or call for emergency medical help.
