Sa Kaeo

Researchers are evaluating the safety, immune response, and effectiveness of the V181 dengue vaccine in healthy children aged 2 to 17 years. This study aims to see if V181 can reduce the number of dengue infections caused by any of the four dengue virus types, regardless of whether participants have had dengue before. The trial is a phase 3, randomized, double-blind, placebo-controlled study sponsored by Merck Sharp & Dohme LLC. Participants will be randomly assigned to receive a single 0.5 mL dose of either the V181 vaccine or a placebo by subcutaneous injection on Day 1. About 3600 participants are included in the Reactogenicity and Immunogenicity Subset, which will be monitored for safety and immune response for 28 days after vaccination. A smaller group of about 620 participants from this subset will be followed for up to 5 years to assess long-term immune response using specific virus neutralization tests. During the study, participants will be monitored for adverse events, vaccine reactions, and dengue infections, including severity and hospitalization rates, up to 5 years after vaccination. Safety assessments include tracking medically attended and serious adverse events. Immune responses will be measured by antibody levels and seroconversion rates. Participants will have scheduled visits during the first month postvaccination and ongoing follow-ups for several years to evaluate the vaccines long-term effects and protective benefits.