system
A chat on subreddit /r/PoliticalCompassMemes
human
I’d be willing to accept that as an answer, but given the violent nature of how football is played, if it simply was blunt trauma to the chest, this wouldn’t be the first time we’ve seen it, across both college and pro leagues. Players get hit in the chest repeatedly, multiple times a game. 

It raises some red flags (for me at least) to attribute it to Commotio Cordis that baseball/softball account for over 70% of all cases and neither of them are contact. Also the average victim age is 15 years old.

I’m not saying the vax did it, but the knee jerk reaction to attribute it to this doesn’t seem like the right call either. I’d like to wait for additional information
gpt
Dr brian sutteror has a youtube channel for sport injuries. The hit has to happen at a specific time of the heartbeat (10% chance) and has to be ... violent and precise, not unlike taking a baseball to the chest. 
15 years old have a lot less chest muscle than an nfl safety, and muscle buffers the impact.