I wish Lymerix was available because I no longer want to have to hike or bike in the great outdoors head to toe in clothing design to avoid tick intrusion, much less worry that I was bitten on an exposed part of my skin. Now I'll just have to do it because my skin is designed to be a solar panel for vitamin D production in the dreariest parts of the Irish winter...
Unless you're in the 5% of the population that's genetically predisposed to poor health outcomes from Lyme disease, I would not worry. Even if you are, I certainly would not worry to the effect of covering yourself from head to toe on a nature hike. The stress from your worry, is likely causing the type of inflammation that would prohibit your body's natural immune system from attacking a pathogenic bacterium.