The purpose of the sutdy is to evaluate the protective efficacy of Recombinant Herpes Zoster Vaccine (CHO Cell) (hereinafter referred to as "the investigational vaccine") in preventing herpes zoster at 13-36 months after complete immunization with the 0- and 2-month immunization schedule in individuals aged 40 years and older.

Inclusion Criteria:

1. Participants in the MKKCT-100-003 study who have completed two doses of the investigational vaccine;
2. Males or females able to provide legal identity certificate;
3. Participants voluntarily agree to participate in the study, and sign the informed consent form;
4. Able to understand the study procedures and participate in all scheduled follow-up visits, and able to comply with the protocol requirements (such as cooperating in filling out questionnaires/scales, and being regularly contacted during the study for evaluation, etc.).

Exclusion Criteria:

1. Participants who plan to use any products (drugs, vaccines, or medical devices) other than the investigational product for the prevention of VZV infection before signing the informed consent form or during the study period;
2. Participants with a history of herpes zoster;
3. Participants with any confirmed or suspected immunosuppressive or immunodeficiency condition caused by diseases (e.g., malignant tumors, human immunodeficiency virus infections, etc.) or immunosuppressive/cytotoxic treatments (e.g., medications used during cancer chemotherapy, organ transplantation, or treatment of autoimmune diseases);
4. Participants who are currently participating in or plan to participate in other clinical trials during the study;
5. Significant underlying diseases or any other condition that, in the opinion of the investigator, may prevent completion of the trial.