In the two years since COVID vaccines became available to the public, they have become a popular target for misinformation. Anti-vaccine activists have made some wild claims: Vaccines alter DNA, cause infertility, and implant magnetic devices for the government to track your every move, without credible scientific evidence. But they have managed to achieve one goal: More Americans than ever are hesitating to get vaccinated.
So any time a person has a rare side effect from COVID vaccines, the news spreads quickly. For example, Florida’s surgeon general recommended that children between the ages of 18 and 39 not receive the mRNA injections, citing a questionable state analysis that claimed the risk of cardiac death increased by 84 percent after immunization. More recently, people were quick to point to Buffalo Bills player Damar Hamlin’s sudden cardiac arrest in early January as the NFL’s mandatory COVID vaccine requirement. Cardiologists, however, were quick to discredit the idea with more realistic medical explanations.
Infectious disease experts have been investigating the risk of myocarditis since the beginning of the pandemic. Thousands of studies have been published on COVID and some have found a connection between myocarditis with both the virus and the vaccines. These are some of the answers we have so far.
What is myocarditis?
Myocarditis is a disease that causes inflammation in a middle layer of the heart muscle called the myocardium. Inflammation affects the function of muscle cells and the electrical system of the heart, causing irregular heartbeats and interfering with the pumping of blood to and from the body. Inflammation is the result of your body’s immune response overreacting to an infection it is currently fighting. Viruses are the common cause of most myocarditis infections and are responsible for 1.5 million cases each year.
Most cases of myocarditis are mild and resolve on their own, says Keren Hasbani, a pediatric cardiologist with Pediatrix Pediatric and Congenital Cardiology Associates of Texas. Most disappear in less than two weeks without complications or the need to go to the hospital.
Myocarditis that persists for more than two weeks is considered chronic and can lead to serious complications. The longer inflammation remains in the heart, the weaker the muscle becomes. Ongoing injury to heart cells can lead to permanent scarring of the heart muscle, which can cause the condition to return and increase the risk of stroke, heart attack, heart failure, or death.
Myocarditis can affect anyone, at any age. However, heart disease appears to occur at twice the rate in young men than in women.
What does myocarditis feel like?
In some cases of myocarditis, a person may show no symptoms and go about their day without knowing that their heart is inflamed. When there are side effects, they can mimic those of a viral infection, such as fever, vomiting, headaches, and sore throat.
For symptomatic cases, the most common presenting sign is discomfort or a feeling of tightness in the chest area. Hasbani says the pain can occur anywhere between the left side and the chest area. Rather than the pain he feels when he pulls a pectoral muscle, Hasbani says chest pain from myocarditis is often described as pain originating much deeper within the body. “People often say it’s different from any kind of chest pain they’ve ever had before.”
People with myocarditis also tend to describe rapid or abnormal heartbeats due to inflammation affecting the electrical system of the heart. Since the organ is not working at its full potential, the blood is not properly distributed to other parts of the body. This can lead to symptoms such as shortness of breath, especially as chest pain makes it difficult to take deep breaths. Lack of oxygen can cause dizziness and fainting. Less common symptoms include swelling in the legs, ankles, and feet due to lack of blood distribution.
While Hasbani says it’s extremely rare, myocarditis can be life-threatening when the weakened heart can’t keep up with the body’s demands. In these scenarios, a person would need to be hospitalized and receive medications such as adrenaline to keep the heart pumping. Doctors may also need to provide a life support machine to oxygenate and pump the blood. This allows the heart to rest and recover from the damage caused by myocarditis.
Is there a relationship between myocarditis and COVID?
COVID infections can cause severe and life-threatening cases of myocarditis, but the overlap is still low. It is estimated that forty out of a million people develop myocarditis 28 days after testing positive. The chances of developing myocarditis are increased among people with severe COVID illness requiring hospitalization and people with pre-existing health conditions, such as high blood pressure and obesity.
A 2021 study from the Centers for Disease Control and Prevention (CDC) found that the risk of myocarditis is 16 times higher among unvaccinated people with COVID than unvaccinated people who never had the disease. It also found that men and adults over the age of 50 are more vulnerable to the condition. Among unvaccinated children younger than 16 years, the risk of myocarditis was 37 times higher in those with COVID infection than in their healthy peers.
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Hasbani says the reason people with myocarditis from a COVID infection have more serious complications is because the body is already overworked dealing with the extensive damage the virus is doing to other organs like the lungs, kidneys, and kidneys. and the gastrointestinal tract. Inflammation in the heart can take a backseat to all other ongoing bodily problems and take longer to resolve. In children younger than 16 years, the CDC speculates that the increased risk of COVID-induced myocarditis might actually be a sign of multisystem inflammatory syndrome, which is a rare but life-threatening condition associated with COVID infections.
Can COVID vaccines cause myocarditis?
Yes, but the chances are extremely rare. An August 2022 study in England estimated the rate of myocarditis-related hospitalizations and deaths in more than 42 million people aged 13 years and over. Subjects consisted of two different groups: individuals fully vaccinated with the AstraZeneca, Moderna, or Pfizer-BioNTech vaccines, and unvaccinated individuals who tested positive for COVID. The researchers found a 0.007 percent, or 2,681 of 43 million vaccinated adults, chance of being hospitalized or dying from vaccine-related myocarditis. Only 0.001 percent occurred within 28 days of receiving a COVID vaccine or booster. A separate study from October 2022 estimated that the risk of myocarditis was seven times higher in unvaccinated people than in vaccinated people.
Until now, only mRNA vaccines have been associated with myocarditis. The risk appears to be higher in people with a second dose of Moderna than with Pfizer-BioNTech, says Jayne Morgan, a cardiologist and clinical director of the COVID task force at Piedmont Hospital in Atlanta. The large study in England last year showed a greater overlap of myocarditis cases with a second dose of Moderna; meanwhile, another 2022 study estimated a two to three times greater likelihood of developing myocarditis after a second Moderna vaccine, with the strongest association being among men and people aged 18-39. Still, Morgan cautions that the rate is small compared to that of COVID-unvaccinated populations.
[Related: Getting COVID more than once might be even worse than we thought]
Although the incidence is low, research suggests that young men under the age of 40 are at the highest risk of developing myocarditis, says Morgan. A September 2022 study in Israel reported 28 mild cases of myocarditis after a third booster of the Pfizer-BioNTech vaccine, out of nearly four million adults. The results showed that men between the ages of 16 and 19 had the highest risk of myocarditis (a 1 in 15,000 chance), followed by men between the ages of 20 and 24. All individuals made a full recovery after spend an average of 3.5 days. at the hospital.
There is no official explanation for why young men are at higher risk of myocarditis. Some COVID researchers have hypothesized that it has something to do with the SARS-CoV-2 spike protein that the mRNA vaccines were designed for triggering an overactive immune response that causes inflammation in the heart. That doesn’t mean the vaccine is causing the infection, Hasbani cautions. Instead, the immune system is responding to the vaccine in a way that cross-reacts with heart cells in the myocardium. The effect is almost always temporary.
Myocarditis existed long before COVID vaccines
Hasbani says that any medical treatment, including vaccinations, has side effects, including those that affect the heart. The smallpox vaccine, for example, helped eliminate smallpox worldwide since 1980, but was later found to carry a 10 percent risk of mild myocarditis.
One likely reason we know more about the myocarditis risks for the COVID vaccine is that “we haven’t vaccinated this many people as quickly for a specific disease and we’ve followed a large population so closely,” he explains. Hasbani.
With all the facts, both experts emphasize that the small risk of myocarditis is not worth all the other serious complications that a COVID infection can have. For example, long-term COVID continues to be a problem for millions of patients and has been associated with much more persistent heart problems. “Giving you and your family a vaccine is much safer than taking a chance on COVID,” Hasbani adds.
If you get myocarditis from the vaccine, there is little chance that the condition will lead to heart failure. A January 2022 analysis of more than 17 million people found 627 cases (or 0.0035 percent) of myocarditis from the COVID vaccine. Of those, 626 people made a full recovery, with one death. To put that in perspective, the National Institutes of Health website states: “Your chance of getting myocarditis after receiving a COVID vaccine is less than the chance of being struck by lightning in your lifetime.”