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Study of new chickenpox vaccine and measles-mumps-rubella vaccine given by intramuscular injection in healthy children aged 12 to 15 months

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What is this trial about?

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

This clinical trial evaluates a new investigational varicella vaccine (chickenpox vaccine) and Priorix (a combination vaccine against measles, mumps, and rubella) when given as injections to healthy children aged 12 to 15 months. The study compares giving these vaccines through different injection methods - either into the muscle (intramuscular injection) or under the skin (subcutaneous injection).

The study aims to determine if the new chickenpox vaccine and Priorix work equally well when given as muscle injections compared to the standard under-the-skin method. The effectiveness will be measured by testing the body's immune response to the vaccines through blood tests taken 43 days after vaccination.

During the study, participants will be monitored for common vaccination reactions like redness, pain, and swelling at the injection site, as well as general symptoms such as drowsiness, decreased appetite, irritability, and fever. They will also be checked for any rashes that may develop after vaccination. The total study duration will be 181 days, during which participants will have regular check-ups to monitor their health and any side effects.

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 vaccination visit

    You will receive two vaccinations during your first visit. Your child must be between 12 and 15 months of age.

    The first vaccine is for chickenpox (varicella), given by injection into the muscle or under the skin.

    The second vaccine is Priorix, which protects against measles, mumps, and rubella, given by injection into the muscle or under the skin.

    Medical staff will examine your child to confirm they are healthy before administering the vaccines.

  2. Step 2

    Initial monitoring period

    For the first 4 days after vaccination, monitor and record any injection site reactions (redness, pain, swelling).

    For 15 days after vaccination, monitor and record if your child experiences drowsiness, loss of appetite, or irritability.

    Monitor your child's temperature for 22 days after vaccination.

    Watch for any rashes for 43 days after vaccination.

  3. Step 3

    Follow-up blood test

    Return to the clinic on Day 43 after vaccination for a blood test.

    This test will check how well your child's immune system has responded to the vaccines.

  4. Step 4

    Extended monitoring period

    Continue to monitor your child's health for a total of 181 days (approximately 6 months) after vaccination.

    Report any medical visits or serious health issues that occur during this period.

  5. Step 5

    Final visit

    Return to the clinic on Day 181 for the final study visit.

    Medical staff will review your child's health and complete the study documentation.

Who can join the trial?

8 criteria

  • Child must be between 12 and 15 months old (from their first birthday until the day before they turn 16 months)
  • Child must be in good health, as confirmed by medical history and examination
  • Parents or legal guardians must provide written consent (or witnessed thumbprint) before any study procedures begin
  • Parents or legal guardians must be able to follow study requirements, including:
    • Completing electronic diaries
    • Attending follow-up visits
    • For children in countries where PCV (Pneumococcal Conjugate Vaccine) is recommended at 12-15 months:
      • Must have received the primary PCV series in first year of life
      • Last PCV dose must have been given at least 60 days before starting the study
      • Both male and female children can participate

Who cannot join the trial?

13 criteria

  • History of allergic reactions to any vaccine components, especially to neomycin (an antibiotic)
  • Previous severe reaction to any measles, mumps, rubella, or varicella vaccines
  • Active, untreated tuberculosis (a bacterial infection primarily affecting the lungs)
  • Currently taking medications that suppress the immune system
  • Blood disorders or recent blood transfusions within the past 3 months
  • Current fever or active infection
  • Pregnancy or planning to become pregnant within 3 months of vaccination
  • History of immunodeficiency disorders (conditions that weaken the body's ability to fight infections)
  • Receipt of any other vaccines within 30 days before the study
  • Participation in another clinical trial within the past 3 months
  • Any serious chronic medical condition that could interfere with study procedures
  • Known or suspected cancer
  • History of seizures or neurological disorders
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Investigated drugs

  • Varicella vaccine (VNS)

    This is an investigational vaccine designed to protect against chickenpox (varicella). It is being tested for intramuscular administration, which means it is injected into a muscle.

  • Varivax (VV)

    This is an approved vaccine that protects against chickenpox. It is administered subcutaneously, which means it is injected under the skin.

  • Priorix (MMR vaccine)

    This is a combination vaccine that protects against three different diseases: measles, mumps, and rubella. In this trial, it is being tested for both intramuscular and subcutaneous administration.

What is already known about the treatment

  • VNS Vaccine

    An investigational varicella vaccine administered intramuscularly, being studied for immunization against chickenpox (varicella) in children aged 12-15 months. This vaccine is currently in Phase 3a clinical trials, comparing its effectiveness with the traditional subcutaneous Varivax vaccine. The primary mechanism of action involves stimulating the immune system to produce antibodies against the varicella-zoster virus (VZV), providing protection against chickenpox infection.

  • MMR Vaccine (Priorix)

    A combined vaccine that protects against measles, mumps, and rubella, traditionally given subcutaneously but being studied for intramuscular administration in this trial. The vaccine works by introducing weakened versions of these three viruses to stimulate the immune system to produce protective antibodies. This well-established vaccine is being evaluated for a new route of administration to potentially improve its delivery while maintaining its proven effectiveness in children.

  • Varivax

    A licensed subcutaneous vaccine used to prevent chickenpox, serving as the control medication in this clinical trial. This established vaccine contains a weakened form of the varicella-zoster virus, which triggers the immune system to produce antibodies that protect against chickenpox infection. It has been widely used in vaccination programs and serves as the current standard for varicella immunization.

Investigated diseases

  • Varicella

    A highly contagious viral infection caused by the varicella-zoster virus that primarily affects children. The disease typically begins with a fever and general feeling of unwellness, followed by the appearance of a characteristic itchy rash. The rash progresses from small red bumps to fluid-filled blisters that eventually crust over. The condition usually spreads across the entire body in waves, with new spots appearing while others are healing. Symptoms typically last between 5-10 days, during which time the virus is most contagious.

  • Measles

    A viral infection that begins with cold-like symptoms including fever, runny nose, and cough. A distinctive red-brown rash appears a few days later, typically starting on the face and spreading downward across the body. The infection also causes characteristic white spots inside the mouth called Koplik's spots. The disease is highly contagious and can spread through airborne particles.

  • Mumps

    A viral infection that primarily affects the salivary glands, causing them to become swollen and tender. The most noticeable symptom is swelling of the parotid glands, which causes the cheeks to puff out. Initial symptoms include fever, headache, muscle aches, and fatigue. The swelling typically appears first on one side before affecting both sides of the face.

  • Rubella

    A viral infection characterized by a distinctive red rash that first appears on the face before spreading to the rest of the body. The condition often begins with mild fever and swollen lymph nodes, particularly behind the ears. The rash typically lasts about three days and may be accompanied by mild joint pain and cold-like symptoms.

Trial detailsLast updated 2 Oct 2026
Age0-17PhasePhase IIITrial ID2024-518840-18-00Protocol code223105Estimated enrolment994 patientsSponsorGlaxoSmithKline Biologicals

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