Varicella-zoster virus (VZV) causes chickenpox (varicella) and shingles (zoster). Antibody is important for control of varicella as evidenced by the role of varicella immune globulin in limiting the severity of disease in immunocompromised persons. Limited information is available regarding the individual viral proteins to which antibodies are produced during primary infection with VZV or after vaccination. Furthermore, commercially available tests to determine seropositivity to VZV after vaccination have limited sensitivity, and improved assays are needed. We will obtain blood from persons with varicella, zoster, and those vaccinated with the varicella (not zoster) vaccine at the NIH Clinical Center and measure immune responses against specific viral proteins, look for virus in the blood, and in some cases measure immune responses against cellular proteins over time. Elucidation of these responses might help to develop more sensitive assays for VZV seropositivity after vaccination and determine how the varicella vaccine protects against varicella.