The U.S. CDC’s Advisory Committee on Immunization Practices (ACIP) met today (June 23rd) to review evidence of rare reports of myocarditis (inflammation of the heart) following mRNA vaccination.


Scientists determined there IS likely an association between mRNA vaccines and myocarditis (inflammation of the heart) in adolescents and young adults—meaning the observed rates are higher than what would normally be expected.

➡️ The reports were more common in males, and after 2nd dose
➡️ This side effect is rare: (0.000095%, or 12.6 per million 2nd doses for young males)
➡️ Thus far most patients responded well to medications and recovered from symptoms.


In their direct benefit-risk assessment, the CDC concluded that the benefits of COVID-19 vaccination strongly outweigh the risks for all age sex groups. Why?

➡️ Teens and young adults have the highest incidence of COVID-19, and new variants means many more infections are likely.
➡️ Since beginning of pandemic, 2,767 COVID-19 deaths have been reported among persons aged 12-29 years in the US.
➡️ Myocarditis generally occurs after viral infections, INCLUDING with SARS-CoV-2.

In a study of 1597 student athletes with a recent SARS-CoV-2 infection, 2.3% had an abnormal heart MRI finding, and 0.31% had clinical symptoms of myocarditis. Both figures are many orders of magnitude higher than the estimated risk of myocarditis after an mRNA vaccine: 0.000095%.

➡️ Besides COVID-19 hospitalization and death, young people risk Long Covid and MIS-C (Multiple System Inflammatory Syndrome in Children).

The CDC estimates that (see attached infographics):

❇️ For Males aged 12-17, for every 1 million 2nd vaccine doses delivered:
215 COVID-19 hospitalizations and 2 deaths are prevented
56-69 additional cases of myocarditis expected

❇️ For Males aged 18-24:
530 COVID-19 hospitalizations and 3 deaths are prevented
45-56 additional cases of myocarditis expected

These benefits are likely conservative estimates according to CDC, as they assume current levels of cases in the US that could rise with spread of Delta variant, and do not account for the benefit of these vaccinations in reducing infections for the wider community.


➡️ Currently, the benefits still clearly outweigh the risks for COVID-19 vaccination in adolescents and young adults
➡️ Continued monitoring of cases, clinical course, and long-term outcomes of myocarditis after mRNA vaccines will be important
➡️ COVID-19 vaccines are recommended for persons 12 years of age and older in the United States

Further reading:

STAT News summary of ACIP meeting

Full ACIP meeting slides

Prevalence of Clinical and Subclinical Myocarditis in Competitive Athletes With Recent SARS-CoV-2 Infection

Previous DP post on myocarditis

Link to Original FB Post