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Study on the Safety and Immune Response of MenACYW Conjugate Vaccine Compared to a Drug Combination in Healthy Infants and Toddlers

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This clinical trial is focused on studying the effectiveness and safety of a vaccine for preventing meningococcal infection in healthy infants and toddlers. Meningococcal infection is a serious illness caused by bacteria that can lead to infections in the brain and spinal cord. The study involves two vaccines: the MenQuadfi vaccine and the Nimenrix vaccine. Both vaccines are designed to protect against four groups of the bacteria: A, C, W, and Y. The purpose of the study is to compare the immune response generated by these vaccines when given to infants at 6 months and again at 12 months.

Participants in the study will receive two doses of either the MenQuadfi vaccine or the Nimenrix vaccine. The first dose will be administered when the infants are between 6 and 7 months old, and the second dose will be given when they are between 12 and 13 months old. The study will monitor the levels of antibodies, which are proteins in the blood that help fight infections, to see how well the vaccines work. The study will also track any side effects or reactions to the vaccines to ensure they are safe for use in young children.

The trial aims to demonstrate that the MenQuadfi vaccine is not less effective than the Nimenrix vaccine in producing an immune response. This will be measured by looking at the levels of antibodies in the blood after vaccination. The study will also observe any immediate or delayed reactions to the vaccines, including any serious adverse events. The results of this study will help determine the best vaccination strategy for protecting young children against meningococcal infection.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial visit and first vaccination

    Upon joining the study, the first step involves an initial visit. During this visit, a healthcare professional will conduct a medical evaluation, which includes reviewing medical history and performing a physical examination to ensure eligibility.

    If eligible, the first dose of the MenACYW conjugate vaccine or Nimenrix will be administered. This vaccine is given as an intramuscular injection, which means it is injected into a muscle. The first dose is given when the infant is between 6 to 7 months old.

  2. Step 2

    Monitoring after first vaccination

    After the first vaccination, there will be a period of monitoring to observe any immediate reactions to the vaccine. This is to ensure the safety and well-being of the participant.

    Participants may be asked to report any side effects or reactions experienced after the vaccination. This information is important for assessing the safety of the vaccine.

  3. Step 3

    Second visit and second vaccination

    The second visit occurs when the participant is between 12 to 13 months old. During this visit, the second dose of the vaccine will be administered.

    Similar to the first dose, the second dose is also given as an intramuscular injection. This completes the 2-dose series of the vaccine.

  4. Step 4

    Monitoring after second vaccination

    Following the second vaccination, there will be another period of monitoring to check for any immediate reactions.

    Participants will again be asked to report any side effects or reactions. This helps in understanding the safety profile of the vaccine.

  5. Step 5

    Follow-up and study completion

    After the second vaccination and monitoring period, there may be follow-up visits or communications to gather additional information about the participant's health and any long-term effects of the vaccine.

    The study is expected to continue until August 2025, and participants will be informed about the completion of the study and any findings that are relevant to their health.

Who can join the trial?

2 criteria

  • Aged 6 to 7 months on the day of inclusion
  • Participants who are healthy as determined by medical evaluation, including medical history, physical examination, and judgment of the Investigator (the doctor or medical professional in charge of the study)

Who cannot join the trial?

8 criteria

  • Participants must not have any serious health conditions that could interfere with the study.
  • Participants should not have a history of severe allergic reactions, especially to vaccines.
  • Participants must not have received any other vaccines within a certain period before the study starts.
  • Participants should not be taking medications that could affect the immune system, such as steroids.
  • Participants must not have any known or suspected immune system disorders.
  • Participants should not have any ongoing infections or illnesses at the time of the study.
  • Participants must not have participated in another clinical trial recently.
  • Participants should not have any conditions that the study doctors believe would make participation unsafe.
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Investigated drugs

  • MenACYW conjugate vaccine

    is a vaccine designed to protect against four types of bacteria that can cause meningitis, which are known as serogroups A, C, W, and Y. This vaccine works by helping the body build immunity against these bacteria, reducing the risk of developing meningitis. In this clinical trial, the vaccine is given to infants and toddlers in two doses, one at 6-7 months and another at 12-13 months, to see how well it works and how safe it is for young children.

  • Nimenrix®

    is another vaccine that also protects against the same four types of bacteria that can cause meningitis: serogroups A, C, W, and Y. Like the MenACYW conjugate vaccine, it helps the body develop immunity to these bacteria. In this study, Nimenrix® is used as a comparison to see if the MenACYW conjugate vaccine is just as effective and safe when given to infants and toddlers at the same ages and intervals.

What is already known about the treatment

MenACYW conjugate vaccine – This vaccine is administered as an injection to infants and toddlers to help protect against meningococcal infections caused by serogroups A, C, W, and Y. It is currently being studied in a Phase III clinical trial to compare its effectiveness and safety to an existing vaccine called Nimenrix®. The main goal is to ensure that the immune response generated by MenACYW is not inferior to that of Nimenrix®. The vaccine works by stimulating the body's immune system to produce antibodies that can recognize and fight off the bacteria responsible for meningococcal disease. It is classified as a conjugate vaccine, which means it combines a piece of the bacteria with a protein to enhance the immune response.

Investigated diseases

Meningococcal Infection – Meningococcal infection is caused by the bacterium Neisseria meningitidis, which can lead to serious illnesses such as meningitis and septicemia. The bacteria are transmitted through respiratory droplets and can colonize the nasopharynx. In some cases, the bacteria invade the bloodstream and spread to the brain and spinal cord, causing inflammation of the protective membranes. Symptoms may include sudden fever, headache, stiff neck, nausea, vomiting, increased sensitivity to light, and confusion. The disease can progress rapidly, and early symptoms may resemble those of the flu. It is important to monitor for any signs of severe illness, especially in young children and infants.
Trial detailsLast updated 7 Oct 2026
Age0-17PhasePhase IIITrial ID2023-508177-85-00Protocol codeMEQ00089Estimated enrolment840 patientsSponsorSanofi Pasteur

sourced from the EU Clinical Trials Register and site verification

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