He was my great uncle. This is the first I'm hearing that it was related to the vaccine. He went into a coma because he coded during a CT scan and was likely without oxygen for some minutes.
I guess we will never really know, and it might not matter at this point, but I spoke to his son on Shabbos, and he said that while there's no way to really know, whatever happened to him was a couple of days after getting the vaccine.
He will forever be remembered for his love and dedication to Yiddishe kinderlach.