Immune response and safety of an investigational chickenpox vaccine and MMR given by muscle injection to healthy 12–15 month-olds

A Phase 3a, Open-Label, Randomized, Controlled Study to Evaluate the Immunogenicity and Safety of Intramuscular Administration of an Investigational Varicella Vaccine and Priorix Compared With Subcutaneous Administration of Varivax and Priorix, When Given as a First Dose to Healthy Children 12 to 15 Months of Age

This trial will test whether GSK's investigational chickenpox vaccine given with MMR as a muscle shot is safe and produces a good immune response in healthy children aged 12 to 15 months, compared with Merck's chickenpox vaccine given under the skin.

Quick facts

• Phase: Phase 3
• Study type: Interventional
• Enrollment: 900 (estimated)
• Ages: 12 Months to 15 Months
• Sex: All
• Sponsor: GlaxoSmithKline (Industry-sponsored)
• Drugs / interventions: nirsevimab, immunotherapy, prednisone
• Locations: 12 sites (Tucson, Arizona and 11 other locations)
• Trial ID: NCT06855160 on ClinicalTrials.gov

What this trial studies

Healthy children between 12 and 15 months will receive either GSK's candidate varicella vaccine with MMR by intramuscular injection or Merck's varicella vaccine given subcutaneously, and some groups will also receive routine childhood vaccines (hepatitis A, PCV13) at the same visit. The study measures immune responses and monitors safety after vaccination using follow-up visits and parent-reported eDiaries. This is a phase 3, late-stage safety and immunogenicity comparison intended to support use of the GSK formulation and different administration practices. Results will show whether intramuscular coadministration produces comparable antibody responses and acceptable safety in this age group.

Who should consider this trial

Good fit: Healthy boys and girls aged 12 to 15 months whose parent or legal guardian can give informed consent and follow study procedures are the intended participants.

Not a fit: Children who are immunocompromised, who have had prior varicella infection, who have known severe allergies to vaccine components, or who fall outside the 12–15 month age window are unlikely to benefit from participation.

Why it matters

Potential benefit: If successful, this could provide an alternative chickenpox vaccine option that works well and can be given intramuscularly alongside other routine infant vaccines, simplifying immunization visits.

How similar studies have performed: Licensed varicella vaccines such as Merck's Varivax have a long track record of good immune responses and safety, while the GSK candidate is a newer formulation being tested against that established vaccine.

Eligibility criteria

Inclusion Criteria:

* Participant's parent(s)/ Legally acceptable representatives (LAR\[s\]), who, in the opinion of the investigator, can and will comply with the requirements of the protocol (e.g., completion of the eDiaries, return for follow-up visits).
* Written or witnessed/thumb printed informed consent obtained from the participant's parent(s)/LAR(s) prior to performance of any study-specific procedure.
* Healthy participants as established by medical history and clinical examination before entering into the study.
* A male or female between, and including, 12 to 15 months of age (i.e., from the day of 1-year birthday until the day before 16 months of age) at the time of the administration of study interventions.
* Only for children in countries where PCV is recommended at 12 to 15 months of age as per national immunization schedule and provided as part of the study interventions:

  * Participant who previously received the primary series of PCV in the first year of life with last dose at least 60 days prior to the administration of study intervention.

Exclusion Criteria:

* History of any reaction or hypersensitivity likely to be exacerbated by any component of the study interventions including hypersensitivity to neomycin or gelatin.
* Any confirmed or suspected immunosuppressive or immunodeficient condition, based on medical history and physical examination (no laboratory testing required).
* Hypersensitivity to latex.
* Major congenital defects, as assessed by the investigator.
* Recurrent history of uncontrolled neurological disorders or seizures.
* History of measles, mumps, rubella, or varicella disease.
* Active untreated tuberculosis.
* Participants with bleeding disorders (e.g., thrombocytopenia or any coagulation disorder).
* Condition that in the judgment of the investigator would make intramuscular injection unsafe.
* Any other clinical condition that, in the opinion of the investigator, might pose additional risk to the participant due to participation in the study.

Prior/Concomitant therapy

* Use of any investigational or non-registered product (drug, vaccine or invasive medical device) other than the study interventions during the period beginning 30 days before the dose of study interventions administration (Day -29 to Day 1), or their planned use during the study period.
* Chronic administration of immune-modifying drugs (defined as more than 14 consecutive days in total) and/or planned use of long-acting immune modifying treatments at any time up to the end of the study.

  \- Up to 90 days prior to the study intervention administration:
* For corticosteroids, this will mean prednisone equivalent \>=0.5 mg/kg/day with maximum of 20 mg/day for pediatric participants. Inhaled and topical steroids are allowed.
* Administration of immunoglobulins and/or any blood products or plasma derivatives.

  \- Up to 180 days prior to study interventions administration: long acting immune-modifying drugs including among others immunotherapy (e.g., tumor necrosis factor-inhibitors), monoclonal antibodies (except the ones not interfering with the immune response to the study vaccines, e.g., nirsevimab), antitumoral medication.
* Previous vaccination against measles, mumps, and rubella.
* Previous vaccination against varicella virus.
* Previous vaccination against hepatitis A virus.
* Only for children in countries where PCV is recommended at 12 to 15 months of age as per national immunization schedule and provided as part of the study interventions, participant who previously received a booster dose of any PCV.

Prior/Concurrent clinical study experience

• Concurrently participating in another clinical study, at any time during the study period, in which the participant has been or will be exposed to an investigational or a non-investigational intervention (drug/invasive medical device).

Other exclusion criteria

* Any study personnel or their immediate dependents, family, or household members.
* Child in care.
* Participants with the following high-risk individuals in their household: • Immunocompromised individuals.
* Pregnant women without documented history of varicella.
* Newborn infants of mothers without documented history of varicella.
* Newborn infants born \<28 weeks of gestation

Where this trial is running

Tucson, Arizona and 11 other locations

• GSK Investigational Site — Tucson, Arizona, United States (Recruiting)
• GSK Investigational Site — Huntington Park, California, United States (Recruiting)
• GSK Investigational Site — Sherman Oaks, California, United States (Recruiting)
• GSK Investigational Site — Coral Gables, Florida, United States (Recruiting)
• GSK Investigational Site — Miami Lakes, Florida, United States (Recruiting)
• GSK Investigational Site — Tampa, Florida, United States (Recruiting)
• GSK Investigational Site — Idaho Falls, Idaho, United States (Recruiting)
• GSK Investigational Site — Dayton, Ohio, United States (Recruiting)
• GSK Investigational Site — Houston, Texas, United States (Recruiting)
• GSK Investigational Site — Lewisville, Texas, United States (Recruiting)
• GSK Investigational Site — Pharr, Texas, United States (Recruiting)
• GSK Investigational Site — Alken, Belgium (Recruiting)

Study contacts

• Study coordinator: US GSK Clinical Trials Call Center

Conditions Chickenpox; Chicken pox; Candidate l varicella vaccine; Varicella; Varivax; Healthy Children