Immunogenicity and Safety of Varicella Vaccine, Live in Healthy Vietnamese Children

Inclusion Criteria:

1. Healthy children aged 1-12 years;

2. Vaccination history:

   • Participants aged 1 year old: no vaccination history with any varicella containing vaccine;
   • Participants aged 2~12 years old: no vaccination history with any varicella containing vaccine, or have received 1 dose of varicella vaccine at least 3 months before enrollment;
3. Participants and/or their legal guardians are able to understand and sign the informed consent/assent voluntarily;
4. Participants are able to comply with the study procedures based on the assessment of the investigator;
5. Participants should provide verifiable identification, to be contacted, and to contact the investigator during the study period.

Exclusion Criteria:

1. Prior history of VZV infection;
2. Have been exposed to VZV at home, day care, school, etc. within 4 weeks before enrollment;
3. Known allergy to vaccines or vaccine ingredients, or serious adverse reactions to vaccines, such as urticaria, dyspnea, angioneurotic edema;
4. Autoimmune diseases, immunodeficiency diseases (including but not limited to systemic lupus erythematosus, ankylosing spondylitis, autoimmune thyroid diseases, asplenia, functional asplenia, and HIV infection);
5. Coagulation disorders (e.g. factor deficiency, platelet disorders), or history of bleeding, hematoma, or bruising following intramuscular injections or venipuncture;
6. Poorly controlled chronic illnesses or history of severe diseases that, including but not limited to cardiovascular diseases, hematological disorders, liver and kidney diseases, digestive system disorders, respiratory diseases, malignancies, and a history of major organ transplantation;
7. Any confirmed or suspected syphilis, hepatitis B or hepatitis C infection;
8. Current or history of severe neurological diseases (epilepsy, convulsions or seizures [excluding history of febrile seizures]) or psychiatric disorders, or presence of a family history of psychiatric disorders;
9. Receipt of ≥14 days of immunosuppressive or other immunomodulatory therapy (prednisone ≥20mg/day, or prednisone ≥2mg/kg/day, or its equivalent), cytotoxic therapy within 180 days prior to screening, or plans for such treatment during the trial;
10. Receipt of blood products or immunoglobulins within 180 days prior to screening, or plans to receive these treatments in the trial;
11. Receipt of other investigational drugs/vaccines within 30 days prior to screening, or plans to receive such drugs or vaccines during the study period;
12. Receipt of attenuated live vaccines or nucleic acid vaccines within 28 days prior to screening, or subunit or inactivated vaccines within 7 days prior to screening;
13. Fever on vaccination day, with axillary temperature >37.2°C pre-vaccination, or vital signs outside normal range, or failure to pass physical examination;
14. Presence of skin injuries, inflammation, ulcers, rashes, scars, or other conditions at the intended injection site that may interfere with drug administration or observation of local reactions;
15. Acute onset of various acute diseases or chronic diseases within the past 7 days, or known or suspected active infections;
16. Any other factors considered by the investigator to make the participant unsuitable for participation in the trial.