ZOSTAVAX is a vaccine designed to prevent shingles (herpes zoster), a painful skin rash caused by the reactivation of the varicella-zoster virus, the same virus that causes chickenpox. It is specifically targeted at older adults, as the risk of developing shingles increases with age. ZOSTAVAX works by boosting the immune system's ability to fight off the virus, thereby reducing the likelihood of developing shingles. The vaccine is administered as a single shot, usually in the upper arm, and is recommended for people aged 50 years and older. While ZOSTAVAX can significantly decrease the risk of developing shingles and the long-term pain that can follow the disease, it is important to note that it does not treat shingles or the nerve pain that may follow an outbreak, nor does it prevent the spread of the virus to other people.