It makes no difference whether you shave or not prior to an injection. As long as you can get the skin itself sterile with the swab before you shoot, you're good to go. The hair follicles are going to remain beneath the skin regardless of whether or not you shave the surface hair off. Getting a tattoo is a lot different than an injection. When you go in to the doc's for a shot of any type, do they shave the area first? Fuck no. I hit the quads on a regular basis and have never shaved, and never will- and never had a problem with it.