Immunogenicity and Safety of SYS6052 in the Participants Aged 40 Years and Above

• Aged 40 years and above, male or female;
• Able to understand the study procedures, comply with the protocol requirements to attend all planned follow-up visits, voluntarily agree to participate in the study, and sign the Informed Consent Form;
• Body mass index (BMI) meeting the requirement: 18.5 ≤ BMI \< 32.5 kg/m²；
• Females of childbearing potential: no sexual intercourse within one menstrual cycle prior to enrollment, or use of effective contraceptive measures; no pregnancy plan within 8 months after enrollment and agreement to use effective contraceptive measures;

Exclusion Criteria:

• History of herpes zoster;
• History of prior vaccination with varicella or herpes zoster vaccines (including investigational vaccines);
• Close contact with a patient with varicella or herpes zoster within 1 year prior to enrollment;
• Axillary temperature ≥37.1℃ on the day of enrollment or within 24 hours prior to enrollment;
• Phase I: blood pressure measured on the day of enrollment: systolic blood pressure ≥140 mmHg or diastolic blood pressure ≥90 mmHg; Phase II: blood pressure measured on the day of enrollment: systolic blood pressure ≥160 mmHg or diastolic blood pressure ≥100 mmHg；
• Abnormal results with clinical significance in laboratory tests (Phase I) or physical examination prior to enrollment；
• History of allergy to any component of the investigational vaccine; or a history of severe allergic reactions to vaccines or drugs (including but not limited to anaphylaxis, allergic laryngeal edema, anaphylactoid purpura, thrombocytopenic purpura, or local allergic necrosis [Arthus reaction]);
• History of demyelinating diseases, including but not limited to Guillain-Barré syndrome, multiple sclerosis, neuromyelitis optica, and acute disseminated encephalomyelitis;
• Current epilepsy or seizures, severe neurological diseases, or psychiatric disorders;
• Contraindications to intramuscular injection, such as local infection or skin lesions at the injection site, severe thrombocytopenia, any coagulation disorder, or ongoing treatment with anticoagulants;
• Known malignancy, malignancy not adequately treated, or malignancy with potential risk of recurrence during the study period;
• Phase I: presence of chronic underlying diseases, including cardiovascular and cerebrovascular diseases, thrombotic diseases, hematologic and lymphatic diseases, hepatic and renal diseases, respiratory diseases, endocrine and metabolic diseases, musculoskeletal diseases, and autoimmune diseases; Phase II: presence of chronic underlying diseases (as described above) with unstable disease control within 3 months prior to enrollment; unstable disease control refers to the need for additional medical interventions or major adjustments to the treatment regimen;
• Immune insufficiency or deficiency diagnosed by a hospital prior to enrollment (including HIV infection); congenital or functional asplenia, or splenectomy;
• Long-term (defined as more than 14 days) systemic use of immunosuppressants, immunostimulants, or other immunomodulatory drugs within 6 months prior to enrollment (e.g., corticosteroids, ≥20 mg/day prednisone or equivalent; however, inhaled and topical steroids are permitted); or planned use of the above agents during the study period;
• Receipt of whole blood, plasma, serum, immunoglobulin, or monoclonal antibodies within 3 months prior to enrollment, or planned receipt of the above products during the study period;
• Blood donation or blood loss of ≥450 mL within 1 month prior to enrollment, or planned blood donation during the study period;
• Vaccination with any other vaccine within 30 days prior to enrollment, or planned vaccination with any other vaccine within 90 days after enrollment;
• Current participation, or planned participation during the study period, in other clinical trials;
• Females of childbearing potential: positive pregnancy test, pregnancy, or lactation prior to enrollment;
• In the investigator's judgment, inability to comply with study procedures or appointments; or any other condition unsuitable for participation in this clinical trial.