To evaluate the lot-to lot consistency of three batches of recombinant herpes zoster vaccine (CHO cell) produced on a commercial scale in subjects aged 40 years and older after receiving 2 doses on a 0, 2 month schedule.

A total of 1200 subjects aged 40 years and older were randomly assigned in a 1:1:1 ratio to three commercial-scale batches (batch 1, batch 2, Batch 3) , with 400 subjects in each group. To demonstrate lot-to-lot consistency in terms of anti-gE antibody GMC between three production lots of the HZ vaccine one month after the second dose.

Inclusion Criteria:

1. A male or female permanent resident aged 40 years and older at enrollment, with valid identity;
2. Subjects voluntarily agree to participate in the study and signed an informed consent;
3. Be able to understand clinical trials, participate in all scheduled visits and comply with the protocol requirements(e.g. completion of the diary cards/questionnaires, return for follow-up visits, have regular contact to allow evaluation during the study);
4. Women of childbearing potential plan to avoid pregnancy and are willing to use effective contraception(e.g. oral contraceptive pills, injectable progestogen, percutaneous contraceptive patches, implants of levonorgestrel, intrauterine device, female and male sterilization or abstinence) within 12 months after the last vaccination, and the uses of the rhythm method alone, withdrawal alone, and emergency contraception, are not acceptable.

Exclusion Criteria:

1. Axillary temperature > 37.0°C on the day of vaccination or acute illness;
2. Current or history of herpes zoster;
3. Previous vaccination against varicella or herpes zoster (either registered product or participation in a previous vaccine study);
4. Pregnant (urine pregnancy test was positive) or lactating female;
5. Receipt of live vaccine within 28 days, or any other vaccine within 14 days prior to vaccination;
6. Receipt of immunoglobulin or intravenous immunoglobulin during 3 months before vaccination, or planned receipt 1 month post the last vaccination;
7. Acute diseases(such as acute upper respiratory tract infection with fever, cough, sore throat) or acute exacerbation of chronic disease within 3 days before vaccination;
8. Receipt of antipyretic, analgesic and allergy drugs within 3 days before vaccination, except enteric-coated aspirin for cardiovascular diseases prevention;
9. A known allergy to any components of the study vaccine, or history of severe allergy (e.g. Anaphylactic shock, allergic laryngeal edema, anaphylactoid purpura, thrombocytopenic purpura, Arthus reaction, severe urticaria) to any previous vaccination;
10. Allergy to aminoglycoside antibiotics;
11. History of convulsions, epilepsy, congenital brain dysplasia, mental illness or family history, or history of brain nerve tissue damage due to other severe neurological disorders(e.g. brain tumor, cerebral hemorrhage, cerebral infarction, brain infection disease, chemical drug poisoning);
12. Asplenia or functional asplenia, or splenectomy caused by any condition;
13. Primary or secondary impairment of immune function, diagnosed congenital or acquired immunodeficiency, human immunodeficiency virus (HIV) infection, lymphoma, leukemia, systemic lupus erythematosus, rheumatoid arthritis, inflammatory bowel disease or other autoimmune diseases;
14. Receipt of Immunosuppressive therapy(such as long-term use of systemic glucocorticoid ≥14 days, ≥20mg/day prednisone or equivalent dose) or long-acting immune-modifying drugs(e.g. Infliximab) during the period starting 6 months before vaccination or planned administration 1 month after the last vaccination, but topical steroids(e.g. ointment, eye drops, inhalants, nasal sprays) that do not exceed the dosage recommended in the instructions or have any systemic signs are acceptable;
15. Patients with severe chronic diseases, including but not limited to severe cardiovascular diseases (pulmonary heart disease, pulmonary edema), severe liver and kidney diseases, and diabetes mellitus with complications;
16. History of thrombocytopenia or other coagulation disorders, which may cause intramuscular injection contraindications;
17. Abnormal and uncontrolled blood pressure during physical examination before vaccination (for subjects aged 40-59: systolic pressure ≥ 140 mmHg and/or diastolic pressure ≥ 90 mmHg; for subjects aged ≥60, systolic pressure ≥ 150 mmHg and/or diastolic pressure ≥ 100 mmHg);
18. History of drug abuse (narcotic drugs, psychotropic drugs);
19. Patients with previous or current malignant tumors (except papillary thyroid cancer);
20. Receipt of investigational or unapproved products (drugs or vaccines) within 6 months before vaccination; or planned participation in another clinical study during the study period;
21. Any condition that, in the opinion the investigator, makes subjects ineligible for the study.