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Immune response and safety of investigational MMRV vaccine (GSKVX000000025896) drug combination compared with standard MMRV vaccine in healthy children 15 months to 6 years

Verified siteRegistered drugNo placebo
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What is this trial about?

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

The study examines healthy children from 15 months to 6 years of age who receive a second dose of a combined vaccine that protects against measles, mumps, rubella and varicella. The investigational product, identified as MMRVNS, is administered by intramuscular injection and is compared with an approved vaccine called ProQuad that contains the same four live, weakened viruses.

The main aim is to show that the immune response created by MMRVNS is not worse than that produced by ProQuad. An immune response means the body makes proteins called IgG antibodies that recognize and help fight each virus; the study measures how many of these antibodies are present after vaccination.

Participants receive a single injection and then have a brief blood draw about six weeks later (day 43) to check antibody levels. They are observed for any side effects at the injection site, fever, rash, or other symptoms for several weeks, with additional safety checks continuing for up to about six months after the shot.

The research process

The trial runs in 7 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Receive vaccine injection

    You will receive a single intramuscular injection of 0.5 ml of the study vaccine. the injection contains live, weakened measles, mumps, rubella, and varicella viruses. the same volume and route are used for the comparator vaccine.

    The injection is administered once, on the day you join the study, and no additional doses are required during the trial.

  2. Step 2

    Short observation period

    After the injection you will remain in the clinic for about 30 minutes while staff observe you for any immediate reaction such as fever, rash, or severe pain.

    If any reaction occurs, it will be recorded and treated according to standard medical practice.

  3. Step 3

    Daily injection‑site monitoring

    From day 1 to day 4 you should check the injection site each day for redness, pain or tenderness, and swelling. record any findings in the diary provided.

    Continue to watch the injection site for a varicella‑like rash up to day 43 and note any occurrence.

  4. Step 4

    Systemic symptom monitoring

    From day 1 to day 15 you should note any feelings of sleepiness (somnolence) or loss of appetite.

    From day 1 to day 22 watch for fever and record temperature if it rises above normal.

    From day 1 to day 43 monitor for any rash that resembles varicella, measles, or rubella and document its appearance.

  5. Step 5

    Blood draw for antibody testing

    On day 43 you will return to the clinic for a blood sample. this sample will be used to measure immunoglobulin g (igg) antibody levels against measles, mumps, rubella, and varicella.

    The results help determine whether the study vaccine produces an immune response comparable to the comparator.

  6. Step 6

    Reporting unsolicited adverse events

    From day 1 up to day 43 you should report any health problem that was not listed in the diary, such as unexpected illness or injury.

    These events will be recorded by study staff as unsolicited adverse events.

  7. Step 7

    Extended safety follow‑up

    From day 1 to day 181 you will be asked to report any medical visits related to the study vaccine, called medically attended adverse events.

    Serious health problems, including those that require hospitalization, will be reported as serious adverse events throughout the same period.

    A final study visit around day 181 will include a brief medical check and review of any remaining safety information.

Who can join the trial?

10 criteria

  • A parent or legally acceptable representative who the doctor believes can follow the study rules.
  • Written informed consent signed by the parent or guardian before any study procedures are done.
  • The child’s agreement, called informed assent, obtained according to local rules.
  • The child must be a healthy participant, as shown by their medical history and a physical examination.
  • If the country gives the second dose of the vaccine between ages 4 and 6, the child must be between 4 and 6 years old at the time of the study injection.
  • The child must have already received a first dose of a varicella‑containing vaccine (chicken‑pox vaccine) during the second year of life.
  • The child must have already received a first dose of a measles, mumps, rubella‑containing vaccine (MMR vaccine) during the second year of life.
  • If the country does not use the 4‑to‑6‑year schedule, the child must be at least 15 months old but not older than 6 years at the time of the study injection, following local regulations.
  • The child must have received a first dose of a varicella‑containing vaccine either in the second year of life or earlier at 11 months, according to the national vaccination schedule, and at least 3 months before entering the study.
  • The child must have received a first dose of a measles, mumps, rubella‑containing vaccine either in the second year of life or earlier at 11 months, according to the national vaccination schedule, and at least 1 month before entering the study.

Who cannot join the trial?

21 criteria

  • History of an allergic reaction to any part of the study vaccine, such as neomycin (an antibiotic) or gelatin (a protein from animal collagen).
  • A medical condition that would make an intramuscular injection (a shot into a muscle) unsafe.
  • Any other health problem that the doctor believes could increase the risk of taking part in the study.
  • Use of any experimental or non‑approved medicine within 30 days before receiving the study vaccine, or plans to use such medicines during the study.
  • Receiving blood products such as immunoglobulins (antibody medicines) or plasma derivatives within 90 days before the study vaccine, or planning to receive them during the study.
  • Taking drugs that change how the immune system works (immune‑modifying drugs) for more than 14 days in a row, or planning to use long‑acting immune‑modifying treatments up to the end of the study. This includes systemic corticosteroids (steroid medicines) taken up to 90 days before the vaccine, and long‑acting drugs such as immunotherapy, monoclonal antibodies, or cancer medicines taken up to 180 days before the vaccine.
  • Having already received a second dose of a varicella (chicken‑pox) vaccine or a measles‑mumps‑rubella vaccine.
  • Using aspirin or other salicylate‑containing products, or planning to use them, for 6 weeks after the study vaccine.
  • Receiving any other vaccine that is not part of the study schedule from 30 days before to 43 days after the study vaccine, including specific rules for flu vaccines and DTaP vaccines (vaccines for diphtheria, tetanus, and pertussis).
  • Participating in another clinical study at the same time.
  • Being an immediate family member, household member, or dependent of study staff.
  • Having a known or suspected condition that weakens the immune system (immunosuppressive or immunodeficient condition).
  • Being a child who is in foster care or under the care of others.
  • Living with high‑risk individuals, such as people with weakened immune systems, pregnant women without proof they had chicken‑pox, newborn babies whose mothers have no proof of chicken‑pox, or premature newborns born before 28 weeks.
  • Allergy to latex (a material used in some medical products).
  • Having an unstable chronic disease (a long‑term condition that is not well‑controlled).
  • Having major birth defects.
  • Having had measles, mumps, rubella, or chicken‑pox (varicella) disease in the past.
  • Having ongoing or uncontrolled neurological problems, such as seizures, brain inflammation, or congenital (present at birth) neurological conditions.
  • Having had fever‑induced seizures (febrile seizures) if you are under 4 years old.
  • Having active, untreated tuberculosis (a bacterial infection of the lungs).
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Investigated drugs

Investigational MMRV vaccine
This is a new vaccine being studied that combines live, weakened viruses for measles, mumps, rubella, and chicken‑pox (varicella) into one injection. The viruses are grown in laboratory cell cultures and then mixed into a liquid that can be given by intramuscular injection. In the trial, this vaccine is given as a second dose to children aged 15 months to 6 years to see if it produces a strong immune response and is safe, compared with an existing vaccine. ProQuad
ProQuad is an already approved vaccine that also contains live, weakened measles, mumps, rubella, and chicken‑pox viruses in a single injection. It is given by intramuscular injection and is used in the study as the standard against which the investigational vaccine is compared. The trial checks whether the new vaccine works at least as well as ProQuad in protecting children and has a similar safety profile.

What is already known about the treatment

  • Investigational MMRV vaccine (live, attenuated)

    This vaccine is given as a 0.5 ml suspension for intramuscular injection. It is currently in a Phase 3a clinical trial and has not yet received regulatory approval. The vaccine is meant to protect against measles, mumps, rubella and varicella in children. It works by using weakened forms of each virus that can safely trigger the body’s immune system to produce protective antibodies, and it is classified as a combined live‑attenuated viral vaccine.

  • ProQuad (MMRV) vaccine

    ProQuad is supplied as a 0.5 ml suspension for intramuscular injection and is an approved, commercially available vaccine. It is used to prevent measles, mumps, rubella and varicella in children and adults. The live, weakened viruses in the product stimulate the immune system to develop lasting protection against each disease. It belongs to the pharmacological class of combined live‑attenuated viral vaccines.

Investigated diseases

  • Measles

    A highly contagious viral infection that causes fever, cough, runny nose, and a red rash that spreads over the body. After an incubation of about 10‑14 days, symptoms appear and the rash develops a few days later. The rash usually fades over a week as the person recovers. The virus spreads through droplets when an infected person coughs or sneezes. It often leads to a brief period of feeling unwell before recovery.

  • Mumps

    A viral infection that primarily affects the salivary glands, especially the parotid glands near the ears. After an incubation of 16‑25 days, swelling and tenderness of the cheeks develop, often accompanied by fever. Swelling usually peaks within a few days and then gradually improves. The virus spreads by respiratory secretions. Most people feel better within a week.

  • Rubella

    Also called German measles, it is a mild viral illness that causes a low fever and a pink rash that starts on the face and spreads to the body. After about 2‑3 weeks of incubation, the rash appears and lasts for a few days. The rash fades as the fever subsides. The infection spreads through respiratory droplets. Many people have only mild symptoms and recover fully.

  • Varicella

    Commonly known as chickenpox, it is a viral infection that produces an itchy rash with small fluid‑filled blisters. After an incubation of 10‑21 days, the rash appears, beginning on the trunk and then spreading to the face and limbs. New spots continue to form for several days, then the blisters crust over and heal. The virus spreads by direct contact with the rash or through the air. The illness usually resolves within two weeks.

Trial detailsLast updated 7 Oct 2026
Age0-17PhasePhase IIITrial ID2025-523274-17-00Protocol code224349 MMRVNS 20-006Estimated enrolment1 209 patientsSponsorGlaxoSmithKline Biologicals

sourced from the EU Clinical Trials Register and site verification

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