Cardiologists can share numbers with patients to help them understand just how rare post-vaccine myocarditis really is.


Myocarditis and the COVID-19 Vaccine: Everything We Know About Post-COVID-19 Vaccine Myocarditis

New information regarding COVID-19 continues to emerge daily. This content was based on the sources available at the time of writing.

By Dr. Payal Kohli, MD, FACC

It was my last new patient after a long clinic day: a 32-year-old young man with bicuspid aortic valve and mild aortic stenosis. I walked in expecting a quick visit but saw an anxious young couple. After a quick introduction and some pleasantries, I got the question, "Can I get a vaccine exemption signed due to my heart condition?"

At first, I thought I must have missed something on my clinical history, and I asked "Why?" The patient and his wife explained that they were attempting to conceive and that they had concerns about myocarditis and the COVID-19 vaccine, which they had both heard could be a potential complication of the messenger RNA vaccines (mRNA), particularly in young men.

With the risk of myocarditis and the COVID-19 vaccine being so small, it wasn't something that had even crossed my mind. In fact, for my patients with cardiac disease, I am unequivocally in support of the vaccine. Yet with the attention on this condition in the popular media, I realized that I should share numbers with this patient to try to help him understand just how rare post-vaccine myocarditis really is.

Myocarditis: A Formidable Foe

As a cardiologist, myocarditis has always been one of the most challenging problems I have faced in treating heart disease. With many heart conditions, physicians can react quickly, but with myocarditis, it is often a waiting game where the prognosis remains uncertain and the disease has to play itself out.

During the COVID-19 pandemic, myocarditis has reared its ugly head following SARS-CoV2 infection, but there have also been rare case reports of myocarditis following mRNA vaccines. According to a JAMA Internal Medicine report, there was an observed incidence of 0.8 cases/1 million doses (after the first dose) and an incidence of 5.8 cases/1 million doses (after the second dose) of mRNA vaccines in individuals studied for 10 days after vaccination.1 Interestingly, all patients with myocarditis in this report were men, aged 20-32 years and none had prior cardiac disease. And although the incidence ratio of myocarditis was lower than the background rate after the first dose (0.38), it increased to 2.7X the background rate after the second dose. Similar findings were reported in The New England Journal of Medicine with a rate ratio of 2.35, driven primarily by the increased risk in young males, who had rate ratios of 8.96 (16-19y), 6.13 (20-24y), and 3.59 (25-29y).2

In another report published in The New England Journal of Medicine from a large healthcare organization in Israel, where widespread administration of the Pfizer mRNA vaccine was undertaken, participants were followed for up to 42 days after the first vaccine dose and a higher incidence of myocarditis was reported than previously suspected.3 They suggested an incidence of 2.13 cases/100,000 overall and an incidence of 10.69 cases/100,000 in men between 16-29 years. Only one case was associated with cardiogenic shock, with 76% of cases being mild and 22% being intermediate. For comparison, these estimates were higher than those reported by the CDC based on the Vaccine Adverse Events Reporting System (VAERS), which was 0.48 cases/100,000 overall and 1.2 cases/100,000 among those aged 18-29 years.4

Diagnosing Myocarditis

The presentation of myocarditis can be variable depending on the degree of left ventricular dysfunction, ranging from mild symptoms to fulminant heart failure. In the JAMA Internal Medicine report, there were 15 confirmed cases of myocarditis postvaccination (2 cases after the first dose, 13 after the second), and 93% (14/15) of those patients reported chest pain 1-5 days after vaccination, with resolution of symptoms with conservative management and no patients requiring intensive care unit admission.

Myocarditis can also present with shortness of breath, palpitations, arrhythmias, and fever. A young patient in whom coronary artery disease is less likely presenting with chest pain, palpitations, or shortness of breath raises the clinical suspicion of myocarditis or pericarditis. For patients with a clinical suspicion of myocarditis, the CDC and American Heart Association recommend serological markers to assist with diagnosis and prognosis, including CKMB and Troponin I or Troponin T.5 Additional markers, such as BNP or pro-BNP, can be associated with cardiac dysfunction as well as the need for mechanical circulatory support and nonspecific markers of inflammation, such as leukocyte count, ESR, C-reactive protein. These can be elevated but do not exclude myocarditis if they are normal.

ECGs are critical not only in diagnosing the disease by ruling out other clinical causes of chest pain, but also in managing and monitoring its complications, such as the development of arrhythmias. Therefore, the ECG remains a fundamental tool for all patients presenting with suspected myocarditis or post-vaccination chest pain.

Stay on top of cardiology trends and best practices by browsing our Diagnostic ECG Clinical Insights Center.

Unanswered Questions to Consider

The American Heart Association and the American College of Cardiology have both endorsed COVID-19 vaccination for all eligible age groups. To me, the real clinical equipoise comes when a patient has had myocarditis after a prior mRNA vaccination. Would you still rechallenge and give a second dose? Factors to consider in that case would be the severity of the index illness, the time since the illness, the patient's underlying risk for COVID-19, and whether it may be prudent to switch from the mRNA to the DNA vaccine instead, with which myocarditis has not been reported.

Talking to Patients

I assured my patient that even though activation of the immune system from the vaccine can lead to rare cases of myocarditis, his risk remains extremely low, despite him being part of the highest risk demographic. Furthermore, if he were to develop this rare complication, his prognosis would be excellent.

Reassuring patients begins with presenting them with the data on incidence and prognosis to help them see the low correlation between myocarditis and the COVID-19 vaccine. Additionally, it's important to reiterate that all professional guidelines societies have endorsed the vaccine for patients. After talking to my patient, he agreed to get the vaccine, and I considered it a big victory.


  1. Anthony S MD et al. Acute myocarditis following COVID-19 mRNA vaccination in adults aged 18 years or older. Journal of the American Medical Association Internal Medicine. Oct. 2021.
  2. Mevorach D MD et al. Myocarditis after BNT162b2 mRNA vaccine against COVID-19 in Israel. The New England Journal of Medicine. Oct. 2021.
  3. Witberg G MD et al. Myocarditis after COVID-19 vaccination in a large healthcare organization. The New England Journal of Medicine. Oct. 2021.
  4. Wallace M and Oliver S. Centers for Disease Control and Prevention. COVID-19 mRNA vaccines in adolescents and young adults: Benefit-risk discussion. June 2021.
  5. Law Y M et al. Diagnosis and management of myocarditis in children. American Heart Association. Jul. 2021; vol. 144: 123-135.

Dr. Payal Kohli, MD, FACC is a top graduate of MIT and Harvard Medical School (magna cum laude) and, as a practicing noninvasive cardiologist, is the managing partner of Cherry Creek Heart in Denver, Colorado.

The opinions, beliefs, and viewpoints expressed in this article are solely those of the author and do not necessarily reflect the opinions, beliefs, and viewpoints of GE Healthcare. The author is a paid consultant for GE Healthcare and was compensated for creation of this article.