What we know about COVID vaccines and 'extremely rare' heart problems

There has been no public announcement about what caused Damar Hamlin’s cardiac arrest after a tackle during a “Monday Night Football” game between the Cincinnati Bengals and the Buffalo Bills on Jan. 2 — but that hasn’t stopped people from speculating. One unfounded claim making the rounds on social media is that the 24-year-old’s medical emergency was caused by the COVID-19 vaccine. This assertion isn’t based on facts, and heart problems after vaccination have been reported in only a very small number of cases.

What we know about COVID vaccines and heart problems

Dr. Phillip Yang, a cardiologist at Stanford Health Care in California, told Yahoo News that heart problems following COVID vaccination are “theoretically possible but extremely rare.”

The Centers for Disease Control and Prevention has said it is monitoring reports of myocarditis, an inflammation of the heart muscle, and pericarditis, an inflammation of the outer lining of the heart, after someone has received the Pfizer or Moderna mRNA vaccine. Symptoms of myocarditis or pericarditis may include chest pain, shortness of breath or “feelings of having a fast-beating, fluttering, or pounding heart,” and cases after vaccination have most often been reported in adolescents and young adult males within a week of the second dose of the Pfizer or Moderna vaccine. While the severity of myocarditis and pericarditis cases can vary, most patients with reported cases who received care “responded well to medicine and rest and felt better quickly.”

But experts stress that myocarditis or pericarditis after vaccination is very uncommon. The CDC said in September that of the more than 123 million people who had received COVID shots, it had verified 131 cases of myocarditis. And data published by the CDC in 2021 found just 12.6 cases per million second doses administered.

Myocarditis and pericarditis are usually triggered by a viral infection. In fact, Yang and others say, you’re more likely to experience heart problems after contracting the coronavirus than after getting vaccinated — though Yang emphasized that heart problems related to the coronavirus are also very rare.

Researchers have also identified a possible association between COVID vaccines and postural orthostatic tachycardia syndrome, or POTS, a common condition affecting nervous system functions such as heart rate and blood pressure and characterized by symptoms such as lightheadedness, brain fog and fatigue. However, instances of POTS after vaccination are also unusual and much less likely to occur as a consequence of COVID vaccination than of the COVID virus itself. A study published in December by researchers at Cedars-Sinai Medical Center found that the risk of developing POTS is five times higher after COVID-19 infection than after vaccination.

“This concern about POTS is something that you don’t see very often after the COVID vaccine. It’s very rare,” Dr. Mitchell Miglis, a clinical associate professor of neurology at Stanford University, told Yahoo News.

“I think the really important point is that the risk of all these heart conditions — including myocarditis [and] pericarditis — it’s much, much higher with COVID infection, and vaccination significantly reduces your risk of severe disease from that. So getting vaccinated is the best way to help prevent these cardiac conditions from COVID.”

COVID vaccines and misinformation

Dr. Jonathan Kim, chair-elect of the American College of Cardiology Sports and Exercise Cardiology Council, told Yahoo News that claims on social media that the COVID vaccine may have caused Hamlin’s cardiac arrest are “completely irresponsible.”

“This is similar to some of these other stories that are circulating on social media, where those with a personal agenda of disinformation are just linking it to the COVID vaccine without any known particulars in each of these cases,” he said.

False claims that vaccines are responsible for more heart problems in athletes have been running rampant on social media and advertised by Fox News’ Tucker Carlson, including one oft-cited number from a blog post stating that 1,598 athletes have suffered cardiac arrest since COVID-19 vaccinations began. But as a fact-checking assessment by the Associated Press and others explain, that erroneous number doesn’t come from a rigorous study; it instead clumps together reports of deaths and medical emergencies of people all over the world from a wide age bracket, including some whose deaths were attributed to conditions other than cardiac arrest, such as cancer.

“There’s been no evidence to link a higher incidence of sudden cardiac arrest and death in athletes since the COVID vaccine,” Kim said. “And certainly anecdotally, in my own experience, we have not seen an uptick in terms of sudden cardiac arrest cases different than before the COVID vaccine.”

Kim said that most causes of sudden cardiac arrest in young athletes “are typically due to an underlying ... heart problem that was preexisting.” Some medical experts have speculated that commotio cordis — a condition causing an abnormal heart rhythm and cardiac arrest after an object strikes the chest at a critical time during a heartbeat — may have led to Hamlin’s collapse.

Miglis pointed out that symptoms of heart problems like myocarditis or pericarditis often tend to be “less dramatic” than what fans witnessed with Hamlin on the football field.

“Symptoms are going to be persistent for a while, and someone wouldn’t just suddenly collapse because of it,” Miglis said of myocarditis and pericarditis. “Things like chest pain and shortness of breath, fatigue, that’s going to be more over several days that someone would notice and then present with that — not just a sudden collapse or sudden cardiac arrest.”

The takeaway

The CDC recommends that everyone 6 months and older get vaccinated for COVID-19, adding that the known risks of COVID illness and its possibly severe complications “far outweigh the potential risks of having a rare adverse reaction to vaccination, including the possible risk of myocarditis or pericarditis.”

“The take-home point is that the best way to prevent myocarditis or an inflammatory cardiac condition in the pandemic setting is to get vaccinated,” Miglis said. “Because your risk of getting that from COVID is much, much higher than from a vaccine.”