A Phase 3 interventional study of NBP608 (Mid Potency) and NBP608 (Low Potency) in Varicella (Chickenpox), sponsored by SK Bioscience Co., Ltd.. Recruiting at 14 sites in 4 countries. Open to participants aged 12 Months to 12 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-09-15.
Sponsored by SK Bioscience Co., Ltd. · Phase 3, Interventional, and Prevention
The goal of this study is to evaluate the safety and immunogenicity of an investigational varicella vaccine in children. Researchers will compare the investigational vaccine, NBP608, with licensed varicella vaccines. The study includes children aged 12 months to 12 years.
Participants will be randomly assigned to receive either the investigational vaccine (NBP608) or licensed varicella vaccines.
Participants will:
Receive two subcutaneous injections of a study vaccine administered. Visit the study clinic seven times over approximately 15 months. Receive follow-up phone calls 7 days after each vaccination to monitor for safety.
This is a Phase III, randomized, Double-blinded, Active-controlled, Multinational, Multicenter study designed to evaluate the safety and immunogenicity of a two-dose regimen of NBP608 in children aged 12 months to 12 years.
Immunogenicity will be assessed using blood samples collected at predefined time points to evaluate immune responses to varicella.
Safety will be evaluated throughout the study by monitoring adverse events (AEs), serious adverse events (SAEs), and adverse events of special interest (AESIs) following vaccination.
Each participant will take part in the study for approximately 15 months, including scheduled clinic visits and follow-up assessments.
Exclusion Criteria:
1. Participants with any acute illness, including fever or clinically significant symptoms, at the time of study vaccination. 2. History of varicella-zoster virus (VZV) infection or recent exposure to VZV.
3. Presence of household contacts at high risk for severe VZV infection 4. History of immunodeficiency, autoimmune disease, or other conditions affecting the immune system.
5. History of bleeding disorders contraindicating vaccination. 6. History of severe allergic reactions to vaccines or vaccine components. 7. History of Guillain-Barré syndrome associated with prior vaccination. 8. Active untreated tuberculosis infection. 9. Any significant medical condition that, in the investigator's judgment, may interfere with study participation or interpretation of results.
10. Prior receipt of any varicella-containing vaccine. 11. Receipt or planned use of vaccines, medications, immunoglobulins, blood products, or immunosuppressive therapies that may interfere with study evaluation, as defined in the protocol.
12. Participation in another clinical study involving an investigational intervention within a protocol-defined timeframe.
13. Study staff, investigators, and their immediate family members.
Participants receive either a one-dose regimen or a two-dose regimen consisting of two subcutaneous injections administered.
Biological: NBP608 (Mid Potency) · Other: Normal Saline (Placebo)
Participants receive either a one-dose regimen or a two-dose regimen consisting of two subcutaneous injections administered.
Biological: NBP608 (Low Potency) · Other: Normal Saline (Placebo)
Participants receive either a one-dose regimen or a two-dose regimen consisting of two subcutaneous injections administered.
Biological: Varivax® · Other: Normal Saline (Placebo)
Participants receive either a one-dose regimen or a two-dose regimen consisting of two subcutaneous injections administered.
Biological: SKYVaricella® · Other: Normal Saline (Placebo)
NBP608 (mid potency) is a live attenuated varicella virus vaccine (Oka/SK strain).
NBP608 (low potency) is a live attenuated varicella virus vaccine (Oka/SK strain).
Varivax® is a licensed live attenuated varicella virus vaccine (Oka/Merck strain).
SKYVaricella® is a licensed live attenuated varicella virus vaccine (Oka/SK strain).
Placebo consisting of normal saline (0.9% sodium chloride solution).
Seroconversion rate of varicella-zoster virus(VZV)
Seroconversion rate of varicella-zoster virus(VZV) IgG antibodies at 6 weeks after each vaccination
Time frame: 6 weeks after each dose.
Geometric mean antibody titer (GMT) of varicella-zoster virus(VZV) IgG antibodies
Geometric mean antibody titer (GMT) of varicella-zoster virus(VZV) IgG antibodies at 6 weeks after the second vaccination
Time frame: 6 weeks after the second dose.
Seroconversion Rates
Proportion of participants who are seronegative prior to vaccination at each specified assessment time point.
Time frame: Time Frame: 6 weeks after each vaccination, 6 months after the second vaccination
Geometric Mean Titers (GMTs)
VZV IgG antibodies at each specified time point.
Time frame: 6 weeks after each vaccination, 6 months after the second vaccination
Geometric Mean Fold Rise (GMFR)
Fold increases in VZV IgG antibody titers
Time frame: from baseline to each post-vaccination timepoint
Geometric Mean Fold Reduction (GMFRd)
Fold reductions in VZV IgG antibody titers
Time frame: from baseline to each post-vaccination timepoint
Immediate reactions
Percentage of participants reporting any immediate reactions following each vaccination.
Time frame: Within 30 minutes
Solicited adverse events
Percentage of participants reporting solicited adverse events following each vaccination.
Time frame: Within 14 days
Unsolicited adverse events
Percentage of participants experiencing any unsolicited adverse events following each vaccination.
Time frame: Within 42 days
Serious adverse events, medically attended AEs, and AEs leading to withdrawal
Percentage of participants experiencing any serious adverse events, medically attended adverse events, or adverse events leading to withdrawal during the study period.
Time frame: during study period
Adverse events of special interest
Percentage of participants experiencing any adverse events of special interest during the study period.
Time frame: during the study period
Plan to share: No
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SK Bioscience Co., Ltd.