Based on the results of a previous clinical PhaseI/II study, GSK1437173A is the lead GSK candidate Herpes Zoster (HZ) vaccine to prevent episodes of HZ (shingles). This phase II study will be subdivided into a primary study (108494) and three extension studies (108516, 108518 & 108520), consisting of one additional visit each at months 12, 24 and 36, respectively, from the first visit of the Zoster-003 primary study onwards. The aim of the primary 108494 study is to evaluate the immunogenicity & safety of different dosages of the GSK1437173A vaccine in healthy elderly population. The study population will be stratified by age. The primary objective of this trial is to select the best dosage of GSK1437173A. The aim of the extension studies is to evaluate the persistence of the immune response induced by the candidate HZ vaccine during a long term period.