Shortly after the first COVID-19 vaccines appeared in 2021, reports of rare cases of heart inflammationor myocarditis, began to surface.
In most cases it has been myocarditis mild and responded well to treatmentalthough up to four potentially mRNA vaccine-related deaths due to myocarditis in adults have been reported worldwide. No known verified deaths of children have been reported based on publicly available data. The exact number remains a subject of highly heated debate due to the variability in the reporting of possible myocarditis-related deaths.
Studies have largely confirmed that the overall risk of myocarditis is significant higher after an actual COVID-19 infection compared to vaccination, and that the prognosis follows myocarditis from the vaccine is better than by infection. The specific risk of myocarditis varies by age and has been debated due to the differing views of a small group of physicians on risk tolerance and support for or against COVID-19 immunization for specific age groups.
If pediatric cardiologistsWe specialized in heart problems relevant to children of all ages. We believe it is important to weigh the risk of myocarditis caused by COVID-19 immunization against not only COVID-19 viral myocarditis, but also against all other complications what COVID-19 can lead to.
Comparison of the risks of myocarditis due to serious illness versus COVID-19 vaccination or infection is difficult to do right, and debate continues which of those outcomes poses a greater risk.
Myocarditis explained
Myocarditis is any condition that causes heart inflammation. A closely related condition called pericarditis refers to inflammation of the outer lining of the heart. For the purposes of this article, we will mainly focus on myocarditis, as it can be a more serious condition. Most cases of myocarditis are caused by infections, especially viral ones.
Myocarditis can be confirmed by a combination of an electrocardiogram, an ultrasound of the heart called an echocardiogram, and some blood tests. When available, cardiac magnetic resonance imaging or MRI is the most accurate method of diagnosing myocarditis that does not involve an invasive procedure.
A mistaken assumption is that all myocarditis is serious, as it implies damage to the heart. However, there are mild cases where there is very little swelling and only temporary damage to the heart are more common than severe cases that require a machine to assist heart function.
Vaccination versus infection risk
The challenge of dissecting risks of myocarditis of viral infection compared to COVID-19 vaccination is due in part to the difficulty of accurately establishing a diagnosis of myocarditis and population numbers.
The United States Vaccine Adverse Event Reporting System, or VAERS – which is an initial reporting system for vaccine side effects – is not sufficient in itself determine the rate of a vaccine-associated side effect. This is because any side effect can be reported and verification of a reported event is only done retrospectively by the Centers for Disease Control and Prevention.
That vetted data is then reported in more robust databases such as the Vaccine safety data link. A very small number of myocarditis cases following COVID-19 vaccination have led to significant long-term consequences such as cardiac arrhythmias. However, such cases do not reflect the majority.
Fortunately, severe myocarditis after mRNA vaccination for COVID-19 is extremely rare. A 2021 study by Scandinavian scientists looking at the comparative risks of myocarditis and cardiac arrhythmias in patients who experienced myocarditis following COVID-19 infection versus immunization found that the risks vary significantly by age group.
This has been touted as a reason not to vaccinate healthy young men against COVID-19. However, the follow-up study showed that the comparative risks of negative outcomes were worse from myocarditis due to COVID-19 infection and other viral myocarditis than from vaccination in all patients over 12 years of age.
And it’s worth noting that as of mid-March 2023, the US is still the world leader in COVID-19 hospital admissions.
There have been too rare cases of myocarditis have been reported with the newer non-mRNA Novovax vaccinealthough we researchers do not yet know the rates at the population level.
Risk of myocarditis by age and sex
A review of all currently available research shows that the risk of myocarditis following COVID-19 vaccination is highest in young men aged 18 to 39 and older teenage boys aged 12 to 17, with the highest risk after the second dose of vaccine. The cause appears to be related to how the immune system processes the mRNA and sometimes generates an excessive immune response.
The risk of myocarditis related to COVID-19 immunization is significantly lower in children under 12 years old and much lower adult men over 50 years of age. The risk of serious illness from COVID-19, especially in those over the age of 50, has been much higher than the risk of myocarditis from COVID-19 vaccination during the pandemic. The risk of vaccination myocarditis is uniformly lower in girls than in boys.
Babies under 6 months old can only get immunity from their mother’s antibodies unless they are exposed to COVID-19 themselves, as vaccines are not available for this age group.
How to parse the risks
While the risks of myocarditis were highest in teenage boys and young men regardless of the cause, severity and outcome of myocarditis after 90 days was much worse when it stemmed from a COVID-19 infection or other viral illnesses. This mirrors our team’s research on the same topic.
This discussion also does not take into account the coagulation and heart attack risks of COVID-19 itself. Because COVID-19 damages blood vessels in all parts of the body, some organ damage can occur, such as kidney failure, blood clots, heart attacks, and strokes.
We recognize that there is a need for more research into how people fare in the medium and long term following a case of immunization-associated myocarditis. That’s why research is being done, and researchers like us are committed to tracking the data for years to come.
COVID-19 risks in children
Although there are far fewer deaths from COVID-19 in children than in adults, COVID-19 is still one of the leading causes of death in children in the USbased on a study from early 2023. But COVID-19 deaths are not the only relevant measure of its effect in children. COVID-19 has also killed more children in a shorter period of time than several other vaccine-preventable diseasesas Hepatitis A And meningitis before the availability of their vaccines.
The argument some have made that fewer children than adults are dying from COVID-19, or that it is often mild in children, has never been an acceptable justification for not doing everything possible to protect children from it. For example, doctors do not stop treating childhood cancer patients simply because there are fewer of them than adult cancer patients. And we’re not stopping the measles vaccines just because most children who get measles only get a mild case.
The main risk that COVID-19 now poses to children is long COVID, followed by the risk of serious illness. The estimated percentage of children who get long COVID, but the symptoms of long COVID, is still debated can be extremely debilitating. These include severe fatigue, brain fog, sleep disturbances, dizziness, nerve pain, and more.
Considering the decision to vaccinate
We believe that the decision to vaccinate against COVID-19 should be based on the patient’s age, other health conditions, the relative risk of vaccines, how much and what type of COVID-19 is prevalent in your community, and patient and family preference.
Two ways suggested by the CDC and the Public Health Agency of Canada to reduce the risk of myocarditis from the COVID-19 vaccine are to choose Pfizer and stagger your doses by at least eight weeks. This is because Pfizer has slightly less myocarditis than Moderna.
Adults who are immunocompromised or other known medical problems worsen the severity of COVID-19 disease still carry the greatest risk of serious illness. They therefore should follow the GGD COVID-19 vaccination schedule with additional boosters, if advised by their doctor.
While COVID-19 immunizations are now not as efficient at preventing viral transmission as the earliest variant, they remain highly effective in reducing serious illness and hospitalization, even in childrenand especially in the high-risk pregnancy.
Fortunately, children have that went much better of COVID-19 infection than adults. The primary risks of severe COVID-19 for children are in babies and infants, as well as children with health problems which put them at great riskchildren with the most major types of congenital heart defects or people with other medically complex conditions. Children in those groups benefit most from the primary COVID-19 vaccine series; therefore, the decision to vaccinate in their case should be easier.
Informed consent provided with vaccination should include a discussion of infection risks. The risk of immunization will never be zero due to variability in immune system responses; therefore, the most up-to-date information available should always be taken into account when making the decision.
