Being a UPS driver is a demanding job, as they are continuously on the go, very similar to soccer player where it is continuous running. By now it should be evident that more often than not these covid shots which been pushed on to people will affect a person’s heart making it react badly to any strenuous exertion. I wouldn’t be surprised if this is what happened to him. Of course, the medical profession will deny it.
Well I had 3 shots before February of 2022 and I was able to climb Half Dome in Yosemite last week while hiking 31 miles with over 22 lbs on my back.