NCT02723773 - A Long-term Follow-up Study (ZOE-LTFU) of Two Studies 110390 (ZOSTER-006) and 113077 (ZOSTER-022) to Assess the Efficacy, Safety, and Immunogenicity Persistence of GSK Biologicals' Herpes Zoster Subunit (HZ/su) Vaccine and Assessment of 1 or 2 Additional Doses in Two Subgroups of Older Adults | Crick | Crick