Anti-vaxxers claim cardiac arrests in sportsmen like Bronny James are suspicious. Here’s why they aren’t

One day in late July, a promising young American basketball player suffered a rare cardiac arrest during practice at a major university.

The year was 1993, and the player was 27-year-old Reggie Lewis, then a shooting guard for the Boston Celtics NBA game. Lewis tragically did not survive, and his jersey number – 35 – was permanently retired.

That example is worth keeping in mind as controversy engulfs the cardiac arrest suffered by University of Southern California (USC) basketballer Bronny James – the 18-year-old son of NBA legend LeBron James – almost exactly 30 years later on Monday 24 July.

In this latest case, Mr James survived, and he is reportedly doing well in hospital.

But tech tycoon Elon Musk, Fox News host Laura Ingraham, and numerous anti-vaccine users on Musk's beleaguered social network Twitter – now rebranded “X” – have immediately seized on the incident and questioned whether it might somehow be related to the Covid-19 vaccine.

So what does the evidence really tell us about young athletes, cardiac arrests, and the Covid-19 jab?

First, let's look at Musk and Ms Ingraham's basic claims.

“We cannot ascribe everything to the vaccine, but, by the same token, we cannot ascribe nothing,” Musk tweeted (or X-ed?) on Tuesday morning. “Myocarditis is a known side-effect. The only question is whether it is rare or common.”

(Myocarditis is a heart problem caused by inflammation of the heart muscle, which in the most serious cases can cause a cardiac arrest.)

Backing him up that evening, Ms Ingraham said: “Today Elon Musk was pilloried for suggesting that the Covid shot might have had something to do with what happened to Bronny.

“No, he may be completely wrong. It's speculation. But we do know that myocarditis is a side-effect of the vaccine. Given everything the so-called experts got wrong during Covid, we shouldn't condemn anyone who is asking questions – as these cases seem to be accelerating.”

Let's put aside the fact that neither doctors nor the James family have said anything to suggest vaccines might be involved here. Ms Ingraham also didn't give any evidence for the idea that cardiac arrests among young athletes are increasing – but we'll come back to that later.

It's true that research has established a link between myocarditis and Covid-19 vaccines, although contrary to Musk’s tweet we do have an idea of how rare it is.

The Centers for Disease Control and Prevention (CDC) has estimated that between the ages of 18 and 29, it affects no more than 11.6 vaccinated young men per 100,000 – that is, around 0.01 per cent.

Another study of nearly 43 million people, published in the American Heart Association’s academic journal Circulation, found that the risk of myocarditis rose for young men under 40 after the second dose of some vaccines. It was still extremely low in absolute terms, at no more than 100 extra cases per 1 million.

But, research shows the risk of myocarditis is considerably higher from contracting Covid-19 than from getting vaccinated against it. The CDC study found that Mr James's age group was 7-8 times more likely to develop the condition after infection than after vaccination.

The Circulation study drew different conclusions, finding vaccines were associated with more myocarditis than infection for men under 40, though not for anyone else. Again, the overall risk was vanishingly small.

However, that this is just the risk of myocarditis, not cardiac arrest. Another study in Circulation this April found no association between Covid-19 vaccination and actual cardiac arrests outside of hospital.

Moreover, all of this is ignoring the elephant in the room: the danger posed by being a young athlete in the first place.

As the case of Reggie Lewis indicates, cardiac arrests among young men who play basketball are, if not exactly common, far from unheard of.

According to the University of Washington's Sports Institute, about 1 or 2 in every 100,000 young athletes experience a sudden cardiac arrest every year.

Men are at higher risk than women, Black men most of all, and the riskiest sports appear to be football and basketball. For male basketballers at the top level of US college sports, the risk is 20 per 100,000 each year.

In fact, sudden cardiac arrest is the leading medical cause of death for college athletes in the US, according to research from long before the Covid era.

That figure comes from a 2011 study by the University of Washington, which found that 45 athletes in the National Collegiate Athletic Association (NCAA) had died of such incidents between 2004 and 2008.

Excluding those who had died of non-medical or traumatic factors, and those whose cause of death was unknown, this represented more than half of the NCAA athletes who died in those five years.

Older basketball fans might remember the sudden death of Hank Gathers, a college player in Los Angeles who died on the court in 1990 from a cardiac arrest.

Basketball and football seem to be most dangerous. According to an NCAA report in 2016, men's basketball and football players account for 50 per cent of sudden cardiac deaths in the NCAA, despite making up only 23 per cent of all male NCAA athletes.

That gives some context to the fact that this is the second time in two years that a USC basketballer has suffered a cardiac arrest. The other was Vincent Iwuchukwu, who collapsed during a summer workout on 1 July 2022 but made a full recovery and returned to play.

While that may seem quite the coincidence, it's not the first such cluster. Three international soccer players died of cardiac arrests between 2003 and 2007, and a basketballer and a footballer died similarly within the space of one year in 1990.

So, although scientists still don't really know why these cardiac arrests are more common for young athletes, the fact that they are more common is well established.

Altogether, we currently have no cause to think that there is anything suspicious about what happened to Bronny James – and approximately 0.0001 reasons to blame the vaccine.