Constanza

Researchers are evaluating the immune response and safety of a new varicella vaccine (VNS Vaccine) compared to an approved vaccine called Varivax (VV) in healthy children. This study focuses on children aged 12 to 15 months who have not had chickenpox or received a varicella vaccine before. The goal is to see how well the second dose of these vaccines works when given three months after the first dose, assessing the body's immune reaction to the virus. Participants receive either the investigational varicella vaccine or the marketed Varivax vaccine as a second dose, given subcutaneously. Some children may also receive other vaccines such as MMR, Hepatitis A, or different types of pneumococcal conjugate vaccines, depending on their country's immunization schedule. Vaccines are given either subcutaneously or intramuscularly according to local recommendations. The study is randomized and observer-blind to compare the effects fairly. During the study, children will be monitored for immune response by measuring specific antibodies against the varicella virus 43 days after the second dose. Researchers will also observe safety and any side effects. Parents or caregivers will provide consent and children will undergo health checks before and during the trial. The total participation is timed around the vaccination schedule with follow-ups to evaluate vaccine effectiveness and safety.