COVID-19Heart DiseaseInfectious DiseasesPreventive Medicine


I’ve already written three blogs about the incidence of myocarditis after receiving an mRNA vaccine for COVID-19. Now here’s a fourth! The previous articles emphasized the following five things:

  1. Most cases of post-vaccination myocarditis occurred in young people, predominantly males under age 25
  2. Most cases (91%) followed Pfizer-BioNTech’s mRNA vaccine
  3. Most cases were mild and resolved quickly
  4. Most cases occurred after the second dose of vaccine
  5. No patients required mechanical ventilation and no deaths have been reported

This fourth article is based on a report in the January 25, 2022 issue of JAMA. The information reported in this article comes directly from VAERS, the Vaccine Adverse Event Reporting System, collected between December 2020 and August 2021 from 192,405,448 individuals older than 12 years of age. 

192,405,448 people received 354,100,845 shots during that period of time. VAERS reported that after 354 Million vaccine shots (354 million!!!) there were only 1991 suspected cases of myocarditis. Of these nearly 2000 cases, only 1626 actually met strict criteria to be diagnosed with myocarditis. Percentage-wise, that’s an infinitesimally small number: .00046%! That’s a very low percentage. But if you’re one of those 1626 cases, it’s a big deal.

Again confirmed are these facts about post mRNA vaccine myocarditis: 

     Rates were higher after the second vaccination

     Rates were higher in young males

     Median time to onset of symptoms was 2 days. 

     98% of patients had high troponin levels, a cardiac enzyme indicating heart muscle injury

     All cases resolved quickly and no deaths were reported.

Important information revealed by this study is the following:

     Vaccine-related myocarditis starts within 2 days of vaccination

     Typical viral myocarditis cases can take weeks or months to fully develop

     Vaccine-related myocarditis resolves much faster than typical viral myocarditis

     Vaccine-related patients recovered quickly treated with only anti-inflammatory drugs

     Typical viral myocarditis does not respond as consistently to anti-inflammatory treatment

     6% of typical adolescent viral myocarditis cases require heart transplant or die.

It is still not known if vaccine-related myocarditis patients will have long-term, negative effects. Only time will give us that answer. My feeling is that these people will probably be ok, but will definitely need close follow-up by physicians cognizant of their situation, and will need serial echocardiograms to evaluate left ventricular function.

Dr. G’s Opinion: From these four blogs, and the references from which they are written, there is no evidence that post-vaccine myocarditis is a reason not to vaccinate teenagers and young adults. Cases of myocarditis are mild, self-limited, and thus far not associated with long-term problems. They are a concern, but 99.9% of physicians will never see a case. 

References: Oster ME, 25 others. Myocarditis cases reported after mRNA-based COVID-19 vaccination in the U.S. from December 2020 to August 2021. JAMA 2020 Jan 25;327(4):332-339. 


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