Bingham Farms

Researchers are evaluating the immune response consistency of three different lots of GSK's investigational varicella vaccine (VNS Vaccine) in healthy children aged 12 to 15 months who have neither had chickenpox nor received varicella vaccination. The study also compares the safety and immune response of the VNS vaccine with an approved varicella vaccine called Varivax. This is a Phase 3a, observer-blind, randomized controlled trial focused on chickenpox prevention in this young population. Participants will receive one of the three lots of the investigational varicella vaccine or one of two lots of the marketed Varivax vaccine, all given by subcutaneous injection. Alongside these vaccinations, some children may also receive other vaccines such as MMR, hepatitis A, or pneumococcal conjugate vaccines (PCV 13, PCV 20, or Vaxneuvance) depending on national immunization schedules and availability. These vaccines are given either subcutaneously or intramuscularly. The study monitors immune responses following vaccination to assess consistency between lots and compares the investigational vaccine to the approved one. During the study, children will be closely monitored with evaluations of their immune response to the varicella virus, specifically measuring seroresponse and antibody concentrations at Day 43 after vaccination. Safety is also carefully assessed throughout the trial. Parents or guardians will provide consent and support adherence to study requirements, including completion of diaries and attending follow-up visits. The total observation period includes vaccination and follow-up to ensure thorough assessment of immune response and safety in this age group.