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You may have heard of the rare adverse effects related to COVID-19 vaccines that take the form of myocarditis (inflammation of the heart muscle) or pericarditis (inflammation of the tissue sac surrounding the heart). These adverse events were not evident in the initial large, randomized trials that led to the approval of COVID-19 vaccines, but they did become evident when rare cases were identified by post-marketing surveillance activities that tracked those vaccines as they were more widely...
You may have heard of the rare adverse effects related to COVID-19 vaccines that take the form of myocarditis (inflammation of the heart muscle) or pericarditis (inflammation of the tissue sac surrounding the heart). These adverse events were not evident in the initial large, randomized trials that led to the approval of COVID-19 vaccines, but they did become evident when rare cases were identified by post-marketing surveillance activities that tracked those vaccines as they were more widely deployed.[1]
A large observational study published in the journal Lancet on June 22, 2022,[2] adds to prior analyses by confirming myocarditis and pericarditis as rare but usually reversible adverse effects associated with COVID-19 messenger RNA (mRNA) vaccination.
Background on myocarditis, pericarditis and COVID-19 vaccines
Myocarditis can reduce the heart’s ability to pump blood, which in turn can result in chest pain; shortness of breath; abnormal heart rhythms; fatigue; leg, ankle or foot swelling; faintness or lightheadedness; and flu-like symptoms.[3] Usually myocarditis resolves, but in severe cases the disease can permanently damage the heart muscle.[4]
Myocarditis can be caused by viral, bacterial and other infections; certain antibiotics and cancer medications; radiation exposure; and certain inflammatory diseases like systemic lupus erythematosus (lupus).[5] In many patients with myocarditis, a cause cannot be identified.[6]
Symptoms of pericarditis include pain behind the breastbone or on the left side of the chest that worsens with coughing when lying down or breathing deeply and eases with sitting up or leaning forward.[7] The pain may spread to the left shoulder or neck. Other signs and symptoms of pericarditis include fatigue, leg swelling, low-grade fever, pounding or racing heartbeat, shortness of breath while lying down, and belly swelling. Pericarditis usually is mild and goes away without treatment.[8]
Causes of pericarditis include viral infections; heart attack; and certain inflammatory diseases, such as lupus and rheumatoid arthritis.[9] Heart damage due to heart attack or heart surgery, cancer and kidney failure also may cause pericarditis.[10]
The mechanism by which COVID-19 infection or vaccination cause myocarditis or pericarditis is not known. Researchers speculate it may be related to an immune response to the viral-surface spike protein that targets heart-muscle cells.[11]
The new study
For the Lancet study,[12] which was funded by the Food and Drug Administration, researchers analyzed insurance claims data from 15.1 million adults (age 18 to 64 years) who together received nearly 16.9 million doses of the Pfizer-BioNTech COVID-19 mRNA vaccine (COMIRNATY) and 10.6 million doses of the Moderna COVID-19 mRNA vaccine (SPIKEVAX) between Dec. 18, 2020, and Dec. 25, 2021. These are the two most frequently administered COVID-19 vaccines in the U.S.
Across the 15.1 million vaccine recipients studied, 411 developed myocarditis or pericarditis within seven days of receiving a COVID-19 mRNA vaccine dose (first or second in the series). Though rare, the rate of such adverse heart events was higher than expected based on pre-COVID (2019) data, particularly for men aged 18 to 25 years (the highest-risk subgroup) after receiving a second vaccine dose.
The researchers concluded that although there is a slight absolute increase in the risk of myocarditis and pericarditis following COVID-19 mRNA vaccination, such adverse events are rare overall, and the benefits of the vaccines for preventing COVID-19 infection outweigh the risks, even for young men.
Prior studies
As useful context for their conclusions, the Lancet researchers cited two recent scientific studies.
The first was guided by the U.S. Centers for Disease Control and Prevention’s expert Advisory Committee on Immunization Practices (ACIP). That study reviewed data pertaining to 296 million COVID-19 mRNA vaccine doses given in the U.S. through June 11, 2021, including 52 million doses administered to people aged 12 to 29. The ACIP analysis found that vaccinated 12- to 29-year-old males (a high-risk age/sex subgroup) experienced up to 47 vaccine-related myocarditis/pericarditis events for every 1 million vaccinations but prevented 560 COVID-19-related hospitalizations and 6 deaths per 1 million vaccinations (no deaths were reported in the vaccine-related myocarditis/pericarditis cases).[13]
A second study conducted in England analyzed data corresponding to nearly 18 million people aged 16 years or older who received at least one mRNA COVID-19 vaccine dose as well as just over 3 million people aged 16 years or older who experienced a COVID-19 infection between Dec. 1, 2020, and Aug. 24, 2021.[14] The researchers identified myocarditis and other adverse heart events following vaccination or infection. They found that COVID-19 mRNA vaccination resulted in 2 to 6 extra myocarditis cases per 1 million vaccinations after one dose and 10 extra myocarditis cases per 1 million vaccinations after a second dose. By comparison, myocarditis case rates among COVID-19–infected persons were elevated by 40 cases per 1 million patients.
What You Can Do
To protect yourself against the worst effects of COVID-19, get fully vaccinated and boosted, including with mRNA COVID-19 vaccines. Regardless of your age, you should monitor yourself for symptoms of myocarditis or pericarditis and contact your doctor immediately for proper diagnosis and treatment if you experience such symptoms.
References
[1] Patone M, Mei XW, Handunnetthi L, et al. Risks of myocarditis, pericarditis, and cardiac arrhythmias associated with COVID-19 vaccination or SARS-CoV-2 infection. Nat Med. 2022;28(2):410-422.
[2] Wong HL, Hu M, Zhou CK, et al. Risk of myocarditis and pericarditis after the COVID-19 mRNA vaccination in the USA: a cohort study in claims databases. Lancet. 2022;399(10342):2191-2199.
[3] Mayo Clinic. Myocarditis. May 20, 2022. https://www.mayoclinic.org/diseases-conditions/myocarditis/symptoms-causes/syc-20352539. Accessed September 7, 2022.
[4] Ibid.
[5] Ibid.
[6] Ibid.
[7] Mayo Clinic. Percariditis. April 30, 2022. https://www.mayoclinic.org/diseases-conditions/pericarditis/symptoms-causes/syc-20352510. Accessed September 7, 2022.
[8] Ibid.
[9] Mayo Clinic. Pericarditis. April 20, 2022. https://www.mayoclinic.org/diseases-conditions/pericarditis/symptoms-causes/syc-20352510. Accessed September 7, 2022.
[10] Ibid.
[11] Patone M, Mei XW, Handunnetthi L, et al. Risks of myocarditis, pericarditis, and cardiac arrhythmias associated with COVID-19 vaccination or SARS-CoV-2 infection. Nat Med. 2022;28(2):410-422.
[12] Wong HL, Hu M, Zhou CK, et al. Risk of myocarditis and pericarditis after the COVID-19 mRNA vaccination in the USA: a cohort study in claims databases. Lancet. 2022;399(10342):2191-2199.
[13] Ibid.
[14] Patone M, Mei XW, Handunnetthi L, et al. Risks of myocarditis, pericarditis, and cardiac arrhythmias associated with COVID-19 vaccination or SARS-CoV-2 infection. Nat Med. 2022;28(2):410-422.
