Safety and Immune Response of the Second Varicella Vaccine Dose in Healthy Children Aged 15 Months to 12 Years

What this Trial Is About

This research aims to evaluate the immune response and safety of giving a second dose of the varicella chickenpox vaccine using a vaccine made by Sinovac in healthy children aged 15 months to 12 years. The study includes 300 participants who have previously received their first varicella vaccine dose at 12 months of age. Participants will be grouped based on the brand of their first vaccine dose. All participants will receive a single 0.5 mL dose of the Sinovac varicella vaccine as their second dose. The study is open-label and includes five groups according to the first vaccine brand received. The individual participation lasts up to 42 days from enrollment to the last visit. Blood samples will be collected before vaccination and 42 days after to assess immune response. During the study, participants will have blood drawn to measure varicella-zoster virus antibody levels before and after vaccination. Researchers will monitor for any adverse reactions up to 42 days and serious side effects up to 180 days after vaccination. The main outcomes measured include antibody concentration and increase 42 days post-vaccination. The total time commitment for each child is a maximum of 42 days from enrollment to their last onsite visit.

Second Dose of Varicella Vaccine in Healthy Children