A parallel-group, prevention, Phase III, modified double-blind, 2-arm, study to investigate the immunogenicity and describe the safety of a quadrivalent meningococcal conjugate vaccine (MenACYW conjugate vaccine) compared with Nimenrix® when administered in a 1+1 schedule in healthy infants and toddlers at 6 and 12 months of age

This study is looking for healthy babies and young children to take part. There are no specific age limits mentioned beyond being a 'healthy infant and toddler', but detailed checks will be done by the study team.

To be eligible, children generally need to be in good health. This means they shouldn't have any serious ongoing medical conditions that might affect how the vaccine works or how safe it is for them. The study team will review your child's medical history to make sure they are a good fit.

It's important that your child hasn't received certain other vaccines recently or had meningococcal disease before. The study staff will explain all the specific requirements in detail to help you understand if your child can take part.

If your child takes part in this study, they will receive two doses of a vaccine. One dose will be given when they are 6 months old, and the second dose when they are 12 months old. They will receive either the new vaccine (MenQuadfi) or the currently used vaccine (Nimenrix). You won't know which vaccine your child receives until after the study is complete, as this is a 'blinded' study to make sure the results are fair.

Throughout the study, your child will have several visits to the clinic for health checks and to provide blood samples. These samples help the researchers measure how well the vaccines are working by checking for antibodies. You will also be asked to keep track of any side effects your child might experience, especially in the days immediately following each vaccination. The total duration of your child's involvement in the study will be around 7-8 months, from the first vaccine dose until a final check-up after the second dose.