SciCheck Digest

Buffalo Bills player Damar Hamlin collapsed on the field and suffered a cardiac arrest moments after taking a hit to his chest during a tackle. While it’s not yet known why his heart stopped, some experts say his condition is most likely due to a heart rhythm problem as a result of that impact. Still, people on social media have baselessly speculated that it was caused by a COVID-19 vaccine.

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Damar Hamlin, a 24-year-old safety for the Buffalo Bills, collapsed during a Jan. 2 game against the Cincinnati Bengals after being hit in the chest during a tackle. 

While Hamlin initially stood up after the play, he almost immediately fell over, and millions watched on live television as medical personnel attempted to resuscitate him. The Bills said early the following morning in a statement that Hamlin had suffered a cardiac arrest, meaning his heart had stopped beating, after the hit, although his “heartbeat was restored on the field.” The team added that Hamlin was “sedated and listed in critical condition” at a hospital in Cincinnati. Early Tuesday afternoon the Bills said Hamlin remained in critical condition. The game was postponed.

Update, Jan. 6: Hamlin’s medical team announced on Jan. 5 that he was awake and his neurological function appeared intact, although it was too early to know if he would fully recover. The following day, the Bills said Hamlin had had his breathing tube removed overnight and was speaking. The game was ultimately canceled.

While the cause of Hamlin’s cardiac arrest is not yet known, some physicians say the most likely cause is an arrhythmia that occurred as a result of the blow to his chest, known as commotio cordis.

Yet online, people have baselessly speculated — some within minutes of the collapse — that Hamlin’s condition is a result of COVID-19 vaccination. is not aware of Hamlin’s vaccination status, but as of Jan. 13, 2022, nearly 95% of NFL players were vaccinated.

“24 year old elite athletes in the NFL don’t just have cardiac arrest in the middle of a prime time game,” reads one post shared on Instagram. “This is squarely on the back of every single person who pushed that poison, required it, and shamed people who didn’t get it.”

Dr. Peter McCullough, a cardiologist known for spreading misinformation about the COVID-19 vaccines, suggestively said that if Hamlin “indeed took one of the COVID-19 vaccines, then subclinical vaccine-induced myocarditis must be considered in the differential diagnosis.” Myocarditis is inflammation of the heart muscle.

Several peopleincluding Charlie Kirk of the conservative group Turning Point USA, alluded to previous, unfounded notions that the vaccines are causing a surge of sudden deaths in young, healthy people, including athletes. There is no evidence for such claims.

Republican Rep. Marjorie Taylor Greene also chimed in on Twitter to suggest a connection between Hamlin and the COVID-19 vaccines. She also pointed to a tweet from last year from the Centers for Disease Control and Prevention about the dangers of relatively common blood clots in veins. The tweet had nothing to do with vaccination, as we’ve written.

Commotio Cordis

It’s premature to know for certain what happened to Hamlin. But expert speculation has been focused on a rare condition known as commotio cordis.

“It’s kind of like a perfect storm of events,” Neel Chokshi, a sports cardiologist at the University of Pennsylvania, told us. “When a blow to the chest wall happens at the right point during the cardiac cycle — or during a heartbeat — it can then trigger an irregular and life-threatening heart rhythm, which causes an individual to arrest.”

According to a 2012 review article, about 10 to 20 cases of commotio cordis are reported each year to a U.S. registry, primarily among adolescent males who play sports. The condition is most common in baseball, but can occur in football. 

Given that Hamlin collapsed just after a blow to the chest and he was able to be resuscitated, Chokshi said commotio cordis is “probably the most plausible explanation, not knowing any other details or any other predisposing conditions.”

Dr. Mark Link, a heart and arrhythmia specialist at UT Southwestern Medical Center, said that other conditions are more commonly the cause of cardiac arrest in a man of Hamlin’s age, but based on the footage, he too said that he thought commotio cordis was the most likely explanation.

Other physicians have come to a similar conclusion based on the available information, although some have also proposed an underlying cardiac condition.

When someone collapses after blunt force trauma to the heart, another main possibility is an aortic rupture or dissection. But Chokshi said that is less likely since Hamlin’s heart started beating again.

There is no evidence that vaccine-related myocarditis is behind Hamlin’s arrest. Myocarditis is a rare side effect of the mRNA COVID-19 vaccines that usually is mild.

Chokshi said that a past history of myocarditis — which can be caused by many things — can in a subset of patients result in scarring in the heart, which could make someone more prone to an irregular heart rhythm. But that’s rare, and typically a patient would be symptomatic with their myocarditis first, Chokshi said. He said it wasn’t impossible, but “highly unlikely” for Hamlin’s arrest to be due to myocarditis of any kind, let alone vaccine-related myocarditis specifically.

Link said vaccine-related myocarditis was very unlikely. A work-up in the hospital would reveal more, he said.

Chokshi similarly said it would be important for doctors to run tests to rule out preexisting causes, including structural abnormalities of the heart. Genetic mutations can also predispose people to heart rhythm problems.

“Vaccine myocarditis is probably the lowest on the list at this point,” he said of possible reasons for Hamlin’s cardiac arrest.

“This is not something that people should go speculate about vaccines or anything like that causing this cardiac arrest,” said Dr. Brian Sutterer, a physical medicine and rehabilitation specialist, in a YouTube video. “There was a clear contact, a clear trauma, and I think a clear reason why, unfortunately, this happened for Hamlin.”