This study evaluates the immunogenicity and safety of three different potencies of NBP608 and Varivax which are indicated for active immunization for the prevention of varicella. Total of 152 subjects (38 subjects per each treatment arm) of 12 months to 12 years of age are enrolled, and each subject is administered with single dose of vaccine which is randomly assigned.

This is a multi-center, randomized, double blinded, active controlled, parallel-group study to evaluate the immunogenicity and safety of three different potencies of NBP608(low, middle, high potency) and Varivax which are indicated for active immunization for the prevention of varicella. Total of 152 subjects (38 subjects per each treatment arm) of 12 months to 12 years of age are enrolled, and each subject is administered with single dose of vaccine which is randomly assigned in 1:1:1:1 ratio. Stratified randomization for age group is used to achieve the balance of treatment assignment within age strata.

Total of four visits are scheduled including two visits via telephone contact. Blood sampling is conducted for immunogenicity assessment before and 6 weeks after vaccination at Visit 1 and Visit 3 respectively. Safety is monitored 1 week, 6 weeks and 26 weeks after vaccination through Visit 2*, Visit 3 and Visit 4* (*telephone contact)

Inclusion Criteria:

• Healthy children aged between 12 months and 12 years old who are available for the follow-up during the study period
• After menarche females who are confirmed to be negative in a pregnancy test on the day of vaccination and agree to practice birth control for 3 months after the vaccination

Exclusion Criteria:

• Those with hypersensitivity to any component of the IPs(Investigational Products), such as gelatin or neomycin
• Those who have received a varicella vaccine previously
• Those with a history of hypersensitivity to vaccination, such as Guillain-Barre syndrome
• Those with congenital or acquired immunodeficiency
• Those with active untreated tuberculosis
• Those who have received or are expected to receive salicylates from 14 days prior to IP(Investigational Product) vaccination to Visit 3
• Those who have received or are expected to receive other vaccines from 1 month prior to IP(Investigational Product) to Visit 3
• Those who have received or are expected to receive other IPs(Investigational Products) in another clinical study from 1 month prior to IP(Investigational Product) vaccination to Visit 3