Myocarditis after mRNA Vaccination in the Military

In the past, myocarditis or inflammation of the heart muscles is rarely seen after vaccination.[1]

Reports of myocarditis in the military prompted this study, Myocarditis Following Immunization With mRNA COVID-19 Vaccines in Members of the US Military. The Journal of the American Medical Association (JAMA) published the study. [2].

Twenty-three men are in the study. Before the myocarditis, they were physically fit by military standards, had no history of cardiac disease, and had no significant cardiac risk factors. They were not exposed to cardiotoxic agents.

All 23 had confirmed COVID-19 more than two months before vaccination. The previous COVID-19 is significant, as we will know later.

The authors pointed out that the myocarditis in this report is higher than expected, especially for those who had a second shot.

The men had the following vaccines: Sixteen had the mRNA-1273 vaccine (Moderna), and 7 had the BNT162b2-mRNA vaccine (Pfizer-BioNTech).

Acute chest pains started 12 to 96 hours after mRNA vaccination. The troponin levels were significantly high. (10-fold to 400-fold the upper limits). Troponin levels reflect heart muscle inflammation.

Three developed the symptoms after the first dose and 20 after the second shot. Other causes of myocarditis like infections, coronary artery disease, or autoimmune disease that can also cause myocarditis are excluded.

All cases satisfied the CDC case definition of myocarditis (see table below).

how did the myocarditis happen?

According to the study authors, the reported myocarditis after mRNA vaccination is highly suggestive of Eosinophilic Hypersensitivity Myocarditis. It is like an allergic reaction manifesting in the heart muscles. [2]

Prior exposure to an allergy-inducing substance is required for hypersensitivity to happen. Previous COVID-19 disease or the first dose vaccination sensitized the immune cells of the men to the spike protein.

When the immune system encounters the spike proteins after the first or second vaccination, the immune system mounts a hypersensitivity response affecting the heart muscle. This allergic response is different from the typical allergic reactions that show as hives in the skin.

In the report, there was more myocarditis among soldiers who had a second shot (20/23). That’s because repeated exposure increases the intensity of the allergic reactions.

Abnormal EKG in myocarditis/pericarditis. Source: James Heilman, MD

What Happened to the men After the Myocarditis?

Sixteen had resolution of symptoms, and seven patients continued to have chest discomfort.

Many say that all young men should get vaccinated. Their logic is that myocarditis also happens in COVID-19, and it may be worse.

COVID-19 Myocarditis in Professional Athletes

Myocarditis can happen in 60% of severe COVID-19 cases, especially those in the older age group and with co-morbidities [2]. But, in a study of young, physically fit men and women, myocarditis outcomes are better.

JAMA Cardiology published a report of 789 professional athletes who tested positive for COVID-19 and had myocarditis. The majority were either asymptomatic or had mild COVID-19. Mild COVID-19 was defined as having loss of taste and smell, nonspecific fatigue, and cough without dyspnea. [5]

All 789 athletes recovered and were able to resume practice. Five were classified as moderate. The authors observed that the moderate cases had more symptoms and required more testing.

Take Away Message

The risks and benefits, specifically for age and medical condition, should always be considered for COVID vaccination.

Excellent physical fitness and early COVID-19 treatment are essential factors in determining milder outcomes for COVID-19 and myocarditis.

Vaccination is a personal decision and should be based on data.

Knowledge about Covid-19 is rapidly evolving. Stay current by subscribing. Feel free to share and like.

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References:

Riccardo Mei et al. Myocarditis and pericarditis after immunization: Gaining insights through the Vaccine Adverse Event Reporting System. International Journal of Cardiology. September 14, 2018, DOI:https://doi.org/10.1016/j.ijcard.2018.09.054
Montgomery J, Ryan M, Engler R, et al. Myocarditis Following Immunization With mRNA COVID-19 Vaccines in Members of the US Military. JAMA Cardiol. 2021;6(10):1202–1206. doi:10.1001/jamacardio.2021.2833
Aslan I, Fischer M, Laser KT, Haas NA. Eosinophilic myocarditis in an adolescent: a case report and review of the literature. Cardiol Young. 2013 Apr;23(2):277-83. doi: 10.1017/S1047951112001199. Epub 2012 Sep 21. PMID: 22995363.
Engler et al. A prospective study of the incidence of myocarditis/pericarditis and new-onset cardiac symptoms following smallpox and influenza vaccination. PLoS One. 2015 Mar 20;10(3):e0118283. doi: 10.1371/journal.pone.0118283. PMID: 25793705; PMCID: PMC4368609.
Martinez MW, Tucker AM, Bloom OJ, et al. Prevalence of Inflammatory Heart Disease Among Professional Athletes With Prior COVID-19 Infection Who Received Systematic Return-to-Play Cardiac Screening. JAMA Cardiol. 2021;6(7):745–752. doi:10.1001/jamacardio.2021.0565

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