I got my booster shot yesterday. I'm on Enbrel and take no other immune suppressing drugs. I got the shot at a grocery store pharmacy. They didn't require any sort of formal proof of my immune-suppressed status. Beware of the side effects. They were much worse for me after the third shot than after the second. I was as sick last night as I've ever been in my life. Fever, chills, and all-over body aches that kept me up most of the night. If you aren't able to easily take off work, I recommend getting the shot on a Friday so you'll have the weekend to recover.