Well yes and no. I have to maintain a rabies titer level. Here, they test our titer one year after the first series of shots. If you have acceptable levels, you get titered every two years after. If the levels are too low, boosters are given to maintain effective antibody levels. This is only done by exposure. You also want to maintain B memory cells specific for the pathogens. This is only done by exposure. Now inoculations can be overused, which can increase allergic reactivity, benign tumors, adjuvant exposure/reactions and other complications. If you give boosters when appropriate, they are effective. I am living proof, haven't had rabies yet...