I got the shots 15/16 years ago. They just wore off this year. Not sure if my new insurance covers them, so I need to see the cost this time around.
You do get sick initially or feel a little shitty if you are really allergic to something...least I did. Bunch of pin pricks in the arm, with shit like Ragweed, pollen, dust mites etc. I went for 2 years for the shots I think...and they lasted 15. Would recommend.