Safety and Immunogenicity Study of GSK Biologicals' Herpes Zoster Subunit (HZ/su) Vaccine GSK1437173A When Administered Subcutaneously Intramuscularly in Adults Aged ≥50 Years

The purpose of this study is to assess the immunogenicity, safety, and reactogenicity of GSK Biologicals' Herpes Zoster (HZ) vaccine (GSK 1437173A) when administered subcutaneously (SC) as compared to intramuscularly (IM) to people 50 years of age and older.

There are 2 treatment groups in this study based upon the mode of vaccine administration.

The humoral immunogenicity (HI) will be measured in all subjects.

Eligibility Criteria:
Inclusion Criteria:

* Subject who, in the opinion of the investigator, can and will comply with the requirements of the protocol.
* Subject, residing in Japan, is of Japanese ethnic origin, defined as having been born in Japan with four ethnic Japanese grandparents and able to speak Japanese.
* Subject has provided written informed consent.
* Subject, male or female, who is 50 YOA or older at the time of the first vaccination.
* Subject, if female, of non-childbearing potential may be enrolled in the study.
* Subject, if female, of childbearing potential may be enrolled in the study, if the subject:

  * has practiced adequate contraception for 30 days prior to vaccination, and
  * has a negative pregnancy test on the day of vaccination, and
  * has agreed to continue adequate contraception during the entire treatment period and for 2 months after completion of the vaccination series (i.e., for 2 months after Month 2).
* Exclusion Criteria:
* Use of any investigational or non-registered product (drug or vaccine) other than the study vaccine within 30 days preceding the first dose of study vaccine, or planned use during the study period.
* Concurrently participating or planned participation in another clinical study, at any time during the study period, in which the subject has been or will be exposed to an investigational or a non-investigational product.
* Administration or planned administration of a live vaccine within 30 days prior to the first study vaccination through 30 days after the second study vaccination.
* Administration or planned administration of a non-replicating vaccine within 8 days prior to or within 14 days after either dose of study vaccine.
* Planned administration, during the study, of an HZ or varicella vaccine (including an investigational or non-registered vaccine) other than the study vaccine.
* Administration of immunoglobulins and/or any blood products within the three (3) months preceding the first dose of study vaccine or planned administration during the study period.
* Chronic administration (defined as \>14 consecutive days) of immunosuppressants or other immune-modifying drugs within six months prior to the first vaccine dose.

  * For corticosteroids, a prednisone dose of \<20 mg/day, or equivalent, is allowed.
  * Inhaled, topical, and intra-articular corticosteroids are allowed.
* Administration or planned administration of long-acting immune-modifying drugs (e.g., infliximab) within six months prior to the first vaccine dose through the duration of the study period.
* History of HZ.
* Previous vaccination against HZ or varicella (registered or investigational product).
* History of any reaction or hypersensitivity likely to be exacerbated by any component of the vaccine or study material and equipment.
* Significant underlying illness that, in the opinion of the investigator, would be expected to prevent completion of the study.
* Any other condition that, in the opinion of the investigator, might interfere with the evaluations required by the study.
* Acute disease and/or fever at the time of vaccination:

  * Fever is defined as temperature ≥37.5°C (99.5°F) for oral, axillary, or tympanic route, or ≥38.0°C/100.4°F for rectal route. The preferred route for recording temperature in this study will be oral.
  * Subjects with a minor illness (such as mild diarrhoea, mild upper respiratory infection) without fever may, be enrolled at the discretion of the investigator.
* Pregnant or lactating female.
* Female planning to become pregnant or planning to discontinue contraceptive precautions (if of childbearing potential) through Month 4 (i.e., 2 months after the second dose of study vaccine).