IT IS A LIVE ATTENUATED VIRUS VACCINE. THE RISK OF DEVELOPING ZOSTER APPEARS TO BE RELATED TO A DECLINE IN VZV-SPECIFIC IMMUNITY. ZOSTAVAX WAS SHOWN TO BOOST VZV-SPECIFIC IMMUNITY, WHICH IS THOUGHT TO BE THE MECHANISM BY WHICH IT PROTECTS AGAINST ZOSTER AND ITS COMPLICATIONS. HERPES ZOSTER (HZ), COMMONLY KNOWN AS SHINGLES OR ZOSTER, IS A MANIFESTATION OF THE REACTIVATION OF VARICELLA ZOSTER VIRUS (VZV), WHICH, AS A PRIMARY INFECTION, PRODUCES CHICKENPOX (VARICELLA). FOLLOWING INITIAL INFECTION, THE VIRUS REMAINS LATENT IN THE DORSAL ROOT OR CRANIAL SENSORY GANGLIA UNTIL IT REACTIVATES.