Inclusion Criteria:

• Adults 60 years of age and older.
• History of Chickenpox.
• Have given written informed consent prior to enrollment.
• History of varicella or long-term (greater than or equal to 30 years) residence in the continental USA.

Exclusion Criteria:

• No history of shingles, no current history of immune suppression (e.g. malignancy or neoplastic disease, corticosteroid therapy).
• No immunosuppression resulting from disease (e.g., malignancy; HIV infection), corticosteroids (except intermittent topical or inhaled corticosteroid [greater than 800 mcg/day beclomethasone dipropionate or equivalent]), or other immunosuppressive/cytotoxic therapy (cancer chemotherapy or organ transplantation).
• No active neoplastic disease (except local skin cancer or other malignancies [e.g., prostate cancer] that are stable in the absence of immunosuppressive/cytotoxic therapy).
• No prior Herpes Zoster.
• No prior receipt of varicella vaccine.
• No allergic sensitivity to neomycin.
• No history of anaphylactoid reaction to gelatin.
• No significant underlying illness that would be expected to prevent completion of the study (e.g., life-threatening disease likely to limit survival to less than 5 years).
• Ambulatory (must not be bed-ridden or homebound).
• No receipt of immune globulin or any other blood product within 3 months before or planned during the 3-5 year study period.
• No receipt of any other immunizations within one month before study vaccination (2 weeks in the case of inactivated influenza vaccines or other non-replicating immunization products [e.g., dT, pneumococcal vaccine, hepatitis A vaccine, hepatitis B vaccine]), or scheduled within 6 weeks after study vaccination.
• Not currently receiving antiviral therapy.
• No other condition (e.g., extensive psoriasis, chronic pain syndrome, cognitive impairment, severe hearing loss) that, in the opinion of the investigator, might interfere with the evaluations required by the study.
• No intercurrent illness (e.g., urinary tract infection, influenza) that might interfere with the interpretation of the study.
• No females who are pre-menopausal.
• No subjects unlikely to adhere to protocol follow-up.
• No subjects involved in a conflicting (vaccine or investigational drug) clinical trial.