First Covid-19 shot

I have a buddy that is a cop in AZ. He has come in contact with all sorts of nasty crap. He was scheduled to get the first shot, started feeling a bit off. Got tested...he had Covid. He told me the worst part was the exhaustion he suffered for the first several days. 14 days after testing positive he got retested. Got the ok to go back to work. Was told on the 90th day from his all clear test he would get the shot. Day 80...Covid again. This time he just got a headache and a mild cough. Got the all clear to return to work, the 90 day counter started again. Day 88 he started feeling off...Covid again. Last we spoke he only made it 35 days before testing positive again. He was the instructor of a firearm recertification day at a weapons range. 3 of the officers that were there that day were not feeling well...my buddy and all 3 tested positive. He did say that each time he pops positive the symptoms are less noticeable. This last time he had a mild headache...but just walking from his bed to the sofa whooped his ***...