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Study on the Safety and Immune Response of a 21-Valent Pneumococcal Vaccine in Healthy Infants, Toddlers, Children, and Adolescents

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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 effects of a new vaccine called Pneumococcal Conjugate Vaccine (PCV21) in healthy infants, toddlers, children, and adolescents. The vaccine is designed to protect against infections caused by the bacteria Streptococcus pneumoniae, which can lead to serious illnesses such as pneumonia, meningitis, and bloodstream infections. The study will compare the new 21-valent vaccine, which targets 21 different types of the bacteria, with an existing 20-valent vaccine known as PREVNAR 20®.

The purpose of the study is to evaluate the safety and immune response of the new vaccine. Participants will receive the vaccine through an injection into the muscle. The study will monitor the participants for any immediate reactions, as well as any other side effects that may occur after receiving the vaccine. The immune response will be measured by checking the levels of specific antibodies, which are proteins in the blood that help fight infections, 30 days after the last dose of the vaccine.

The study will involve several visits over a period of time to ensure the safety and effectiveness of the vaccine. Participants will be observed for any adverse events, which are any unwanted effects that occur after receiving the vaccine. The study aims to provide valuable information on how well the new vaccine works in different age groups and its potential to offer broader protection against pneumococcal diseases.

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

    Upon joining the study, a medical evaluation is conducted. This includes reviewing medical history and performing a physical examination to ensure eligibility.

    Consent forms must be signed by the participant or their legal representative. For adolescents, a pregnancy test may be required.

  2. Step 2

    First vaccination

    The first dose of the 21-valent pneumococcal conjugate vaccine (PCV21) is administered through an intramuscular injection. This is a shot given into a muscle.

    Participants are monitored for any immediate reactions following the injection.

  3. Step 3

    Follow-up visits

    Several follow-up visits are scheduled to monitor health and any reactions to the vaccine.

    During these visits, any side effects or adverse events are recorded. Blood samples may be taken to measure antibody levels.

  4. Step 4

    Second vaccination

    A second dose of the PCV21 may be administered, depending on the study group and schedule.

    Similar to the first vaccination, monitoring for immediate reactions is conducted.

  5. Step 5

    Final evaluation

    A final evaluation is conducted to assess the overall health and immune response.

    Participants may be asked about any side effects experienced throughout the study.

Who can join the trial?

7 criteria

  • Aged 7 months to 17 years on the day of inclusion
  • Participants who are healthy as determined by medical evaluation, including medical history and physical examination
  • For infants (7 to 11 months old) and toddlers (12 to 23 months old) only: Born at full term of pregnancy (at least 37 weeks) and with a birth weight of at least 2.5 kg, or born after a gestation period above 28 weeks through 36 weeks with a birth weight of at least 1.5 kg, and in both cases medically stable as assessed by the investigator
  • For adolescents (6 to 17 years old) only: A female participant is eligible to participate if she is not pregnant or breastfeeding and one of the following conditions applies:
    • She is of non-childbearing potential. To be considered of non-childbearing potential, a female must be pre-menarche (before the first menstrual period) or surgically sterile.
    • She is of childbearing potential and agrees to use an effective contraceptive method or abstinence from at least 4 weeks prior to the study vaccine administration until at least 4 weeks after the study vaccine administration. A female participant of childbearing potential must have a negative highly sensitive pregnancy test (urine or blood test as required by local regulation) within 25 hours before the first dose of study vaccine.
    • An assent form has been signed and dated by the participant (based on local regulations), and if applicable, an informed consent form has been signed and dated by the parent(s) or another legally acceptable representative and by an independent witness, if required by local regulations
    • Participant and parent(s) or legally acceptable representative(s) are able to attend all scheduled visits and to comply with all study procedures

Who cannot join the trial?

9 criteria

  • Participants cannot have received any other **pneumococcal vaccine** before the study. A pneumococcal vaccine is a shot that helps protect against infections caused by the bacteria called pneumococcus.
  • Participants should not have any **serious chronic illnesses**. Chronic illnesses are long-lasting health conditions that require ongoing medical attention.
  • Participants must not have a history of **severe allergic reactions** to any vaccine. Severe allergic reactions can include symptoms like difficulty breathing, swelling, or a rash.
  • Participants should not have any **immune system disorders**. These are conditions where the body's defense system against infections does not work properly.
  • Participants must not be taking any medications that affect the **immune system**. These medications can change how the body fights infections.
  • Participants should not have any **bleeding disorders**. Bleeding disorders are conditions that affect the way blood clots, which can lead to excessive bleeding.
  • Participants must not have any **neurological disorders**. Neurological disorders affect the brain, spine, and nerves, and can include conditions like epilepsy or multiple sclerosis.
  • Participants should not be pregnant or planning to become pregnant during the study.
  • Participants must not have participated in another clinical trial within the last 30 days.
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Investigated drugs

  • 21-valent pneumococcal conjugate vaccine (PCV21)

    is a vaccine designed to protect against 21 different types of pneumococcal bacteria. These bacteria can cause serious infections like pneumonia, meningitis, and bloodstream infections. The vaccine works by helping the body build immunity against these bacteria, reducing the risk of getting sick from them. In this clinical trial, the vaccine is being tested to see how safe it is and how well it helps the body produce protective antibodies in infants, toddlers, children, and adolescents.

  • 20-valent pneumococcal conjugate vaccine (20vPCV)

    is another vaccine that protects against 20 types of pneumococcal bacteria. Like the 21-valent vaccine, it helps the body develop immunity to prevent infections caused by these bacteria. In the trial, this vaccine is used as a comparison to see how the new 21-valent vaccine performs in terms of safety and the ability to generate protective antibodies in the participants.

What is already known about the treatment

PCV21 – PCV21 is a vaccine administered through an injection to help protect against infections caused by pneumococcal bacteria. It is currently being studied in clinical trials to assess its safety and effectiveness in infants, toddlers, children, and adolescents. The main purpose of this vaccine is to prevent pneumococcal diseases, which can lead to serious infections like pneumonia. PCV21 works by stimulating the body's immune system to produce antibodies that recognize and fight off the bacteria. It belongs to the pharmacological class of vaccines, specifically designed to prevent bacterial infections.

Investigated diseases

Pneumococcal Disease – Pneumococcal disease is an infection caused by the bacterium Streptococcus pneumoniae, also known as pneumococcus. It can lead to various illnesses, including pneumonia, meningitis, and bacteremia. The disease often begins with symptoms such as fever, chills, cough, and chest pain. In more severe cases, it can progress to cause difficulty breathing, confusion, and a stiff neck. The bacteria can spread from person to person through respiratory droplets. The progression and severity of the disease can vary depending on the individual's age and health status.
Trial detailsLast updated 2 Oct 2026
Age0-17PhasePhase IIITrial ID2024-512271-13-00Protocol codePSK00010Estimated enrolment1 402 patientsSponsorSanofi Pasteur Inc.

sourced from the EU Clinical Trials Register and site verification

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