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Can COVID-19 Vaccines Cause Myocarditis?

By / / COVID-19 vaccine, myocarditis, Rochelle Walensky, safety signals, SARS-CoV-2, smallpox vaccine, VaST

Update – The CDC is reviewing 226 cases of myocarditis in teens and young adults who had very recently received their COVID vaccines. (see below)

Why do some folks think that COVID-19 vaccines can cause myocarditis?

This computer translated article describes the reports of post COVID-19 vaccine myocarditis in Israel.
This computer translated article describes the reports of post COVID-19 vaccine myocarditis in Israel.

A report from the Ministry of Health of Israel in which they state that they have discovered 62 cases of myocarditis and peri-myocarditis, mostly in young men who had recently received a Pfizer COVID-19 vaccine.

Can COVID-19 Vaccines Cause Myocarditis?

Does that mean the Pfizer COVID-19 vaccine causes myocarditis?

Of course not!

What it means is that they found a possible safety signal and it needs to be further investigated.

It is reassuring that no one else has found this signal, although it does seem to be true that Israel has vaccinated more young people than most other countries, and it was these young people who developed myocarditis.

“We have not seen a signal, and we’ve actually looked intentionally for the signal in the over 200 million doses we’ve given.”

Rochelle Walensky, Director of the CDC on Press Briefing by White House COVID-19 Response Team and Public Health Officials

Wait, what is myocarditis?

“In simple terms, myocarditis is a disease that causes inflammation of the heart muscle. This inflammation enlarges and weakens the heart, creates scar tissue and forces it to work harder to circulate blood and oxygen throughout the body.”

Discover Myocarditis Causes, Symptoms, Diagnosis and Treatment

Although it certainly sounds scary, fortunately, many cases of myocarditis go away. And that’s good, because myocarditis is likely not as rare as most people think.

“The incidence of myocarditis is approximately 1.5 million cases worldwide per year. Incidence is usually estimated between 10 to 20 cases per 100,000 persons. The overall incidence is unknown and probably underdiagnosed.”

Viral Myocarditis

In fact, it is thought that “1% to 5% of all patients with acute viral infections may involve the myocardium,” including common childhood infections like parvovirus B-19 (Fifth disease) and human herpesvirus 6 (roseola).

Interestingly, there have been rare reports of cardiac complications, including myocarditis and pericarditis, after adults get the smallpox vaccine.

“Reports of cardiac complications – including myocarditis, pericarditis, and arrhythmias – following smallpox vaccination, have dated back to the 1950s in the United States, although a total of only six such cases were reported prior to 2003.”

Myocarditis and pericarditis are rare following live viral vaccinations in adults

But not after other vaccines.

“We found that the rate of myocarditis and pericarditis in the 42 days following VZV, YFV, OPV, or MMR vaccination was very low and was not statistically different than the rate of these events during unexposed, control intervals. These findings confirm that cardiovascular complications related to commonly-administered, live viral vaccination are rare in adults.”

Myocarditis and pericarditis are rare following live viral vaccinations in adults

Including other live vaccines.

CDC Investigating Myocarditis After Receipt of COVID Vaccines

But isn’t the CDC investigating reports of myocarditis after COVID vaccinations?

“The VaST session on May 17, 2021, included several presentations on myocarditis following mRNA vaccines, from the Department of Defense (DoD), the Vaccine Adverse Event Reporting System (VAERS), and Vaccine Safety Datalink (VSD). There were also brief updates from the Veteran’s Administration (VA) and the Clinical Immunization Safety Assessment (CISA) groups about their plans for future investigation of myocarditis.”

COVID-19 VaST Work Group Technical Report – May 17, 2021

It shouldn’t be a surprise that they are!

“For initial evaluation, consider an ECG, troponin level, and inflammatory markers such as C-reactive protein and erythrocyte sedimentation rate. In the setting of normal ECG, troponin, and inflammatory markers, myocarditis or pericarditis are unlikely.”

Clinical Considerations: Myocarditis and Pericarditis after Receipt of mRNA COVID-19 Vaccines Among Adolescents and Young Adults

While they originally “concluded that there are relatively few reports of myocarditis to date,” more cases have been found as they have been continuing to monitor this situation. The CDC recently presented more information about myocarditis reports to VAERS and from the Vaccine Safety Datalink system at a recent Vaccines and Related Biological Products Advisory Committee meeting.

Call your health care provider if you develop chest pain, especially if the pain gets worse when you lie down, take a deep breath, or cough, and gets better when you sit up, as it could be a sign of myocarditis.
Call your health care provider if you develop chest pain, especially if the pain gets worse when you lie down, take a deep breath, or cough, and gets better when you sit up, as it could be a sign of myocarditis.

And from these new reports, we know that:

  • while there are more reports of myocarditis, it still hasn’t risen to a statistically significant level at which experts can definitely say that the vaccines are the cause.
  • the great majority of these folks with myocarditis, which again sounds very scary, have chest pain, elevated cardiac enzymes when blood tests are done, and ST or -T wave changes when an EKG is done. Fewer have shortness of breath and very few have an abnormal echocardiogram!
  • the episodes were more common in males after their second dose of an mRNA COVID vaccine
  • the great majority of these folks with myocarditis quickly get better with a full recovery!
  • these patients can usually return to their normal daily activities after their symptoms improve, and they should speak with their doctor about return to exercise or sports, following the recommendations from the American Heart Association and the American College of Cardiology

We also know that the cases are now above baseline levels, a sign that they may be more than just a coincidence.

Millions of doses of COVID vaccines have been given in teens and young adults.
Millions of doses of COVID vaccines have been given in teens and young adults.

Again, it is important to remember that most of the cases were mild.

“The known and potential benefits of COVID-19 vaccination outweigh the known and potential risks, including the possible risk of myocarditis or pericarditis. Also, most patients with myocarditis and pericarditis who received care responded well to medicine and rest and quickly felt better.”

Myocarditis and Pericarditis Following mRNA COVID-19 Vaccination

Also, know that these cases are not common!

Millions of doses of COVID vaccines have been given to teens and young adults.

So the possible risk of myocarditis is certainly not a reason to skip or delay getting a COVID vaccine!

Vaccine Preventable Diseases Cause Myocarditis

We also know that many viral and bacterial infections, including many vaccine-preventable diseases can cause myocarditis.

“Where available, evaluate for potential etiologies of myocarditis and pericarditis, particularly acute COVID-19 infection (e.g., PCR testing), prior SARS-CoV-2 infection (e.g., detection of SARS-CoV-2 nucleocapsid antibodies), and other viral etiologies (e.g., enterovirus PCR and comprehensive respiratory viral pathogen testing).”

Clinical Considerations: Myocarditis and Pericarditis after Receipt of mRNA COVID-19 Vaccines Among Adolescents and Young Adults

From diphtheria and chicken pox to measles, mumps, rubella, and flu, many vaccine preventable diseases are known to cause myocarditis and other heart conditions.

Not surprisingly, so can a natural COVID-19 infection.

“Pericarditis and myocarditis with clinical stability are frequent long after SARS-CoV-2 infection, even in presently asymptomatic subjects. These observations will probably apply to the general population infected and may indicate that cardiac sequelae might occur late in association with an altered (delayed) innate and adaptative immune response.”

Pericarditis and myocarditis long after SARS-CoV-2 infection: a cross-sectional descriptive study in health-care workers

What is surprising is that we are seeing myocarditis and pericarditis in some people long after they have recovered from their initial SARS-CoV-2 infection, sometimes in folks who were initially asymptomatic!

“If you have been diagnosed with COVID-19, it’s important to consult with your doctor immediately if you have shortness of breath, chest pain, or heart palpitations. These symptoms may indicate myocarditis as a complication of having the virus.”

Symptoms of Coronavirus That May Point to Possible Myocarditis

Or maybe not so surprising…

Remember, many common viral diseases, often without symptoms, can cause myocarditis.

So why not SARS-CoV-2 too?

But the fact that so many common viral diseases, often without symptoms, can cause myocarditis offers a clue as to why you might find some folks with myocarditis after they get a COVID-19 vaccine.

More on Vaccines and Myocarditis

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