An unfounded belief Covid vaccines are leading to a rise in heart problems, especially in young athletes, has been amplified by Twitter owner Elon Musk.

Bronny James - son of basketball legend LeBron James - suffered a cardiac arrest on Monday while practising.

In a tweet about the incident, Mr Musk said that "we cannot ascribe everything to the Covid vaccine, but by the same token we cannot ascribe nothing".

But there is no evidence to support the implication vaccines might be involved.

Mr James' family has thanked the doctors who helped him, and asked for privacy.

Twitter - which is in the process of rebranding itself as X - allows its users to produce "community notes". These notes add further information to any Tweet considered misleading.

A community note contextualising Mr Musk's comments initially appeared under his tweet, but it was removed overnight.

It's not clear whether the note was removed by Twitter or because it was "downvoted" by other users.

Twitter has not yet responded to our request for comment.

In his tweet, Mr Musk also wrote that, "myocarditis is a known side effect," in response to a post detailing Mr James' hospital admission.

We have no information to suggest Mr James's cardiac arrest was linked to myocarditis - inflammation of the heart muscle - or to the vaccine.

Pfizer and Moderna's Covid vaccines have been linked to relatively rare cases of myocarditis, but crucially, studies suggest this does not lead to have a higher risk of having a cardiac arrest.

Myocarditis is more common and serious after Covid infections than after a vaccine. (BBC)

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