Recurrent chickenpo. When first infected with chickenpox (varicella) the virus remains alive in your nervous system for the rest of your life and for unclear reasons can recur, often in localized area of your body (on one side only). This latter rash is called zoster and a person who has never had chickenpox can "get" chickenpox from this rash, .
Re-activation of grm. Shingles is a condition where the zoster virus emerges from hibernation in one of your nerve roots. It went there after giving you chickenpox & being controlled by the immune system. As it emerges, it travels down the nerve and exits in the distribution of that nerve where it causes pain, blisters and skin sensitivity. U can't get zoster unless u hah chickenpox or the CP vaccine.