This clinical trial is focused on studying Herpes Zoster, commonly known as shingles, which is a painful skin rash caused by the reactivation of the chickenpox virus. The study is evaluating a vaccine called Shingrix, which is designed to prevent shingles. Shingrix is a type of vaccine that uses a part of the virus, known as a recombinant varicella zoster virus glycoprotein E, to help the body build protection against the disease.

The purpose of this study is to assess how well the Shingrix vaccine works over a long period, how safe it is, and how long the immune response lasts in older adults. Participants in the study will receive one or two additional doses of the vaccine. The study will follow participants for several years to monitor their health and the effectiveness of the vaccine in preventing shingles.

Throughout the study, participants will have regular check-ups to track their immune response and any side effects. The study will also look at the number of confirmed cases of shingles among participants and measure specific immune cells and antibodies that help protect against the virus. This information will help determine the long-term benefits and safety of the Shingrix vaccine for preventing shingles in older adults.