In this LTFU study (ZOSTER-060), subjects who received 2 doses of HZ/su in the earlier Zoster-003 (NCT00434577) study will be followed up at Month 108/Year 9 and Month 120/Year 10 post first dose of vaccine for safety and immunogenicity (humoral and cellular). In order to assess the effect of re-vaccination with 2 additional doses of HZ/su vaccine, all the subjects will receive 2 additional doses of the HZ/su vaccine, on a 0, 2-month schedule at ten years after the initial vaccination course in study Zoster-003 (NCT00434577), and will be followed for reactogenicity, safety and humoral and cellular immunogenicity (including persistence).