Second-dose chickenpox vaccine given three months after the first dose for 12–15 month olds

A Phase 3a, Observer-blind, Randomized, Controlled, Study to Evaluate the Immunogenicity and Safety of an Investigational Varicella Vaccine Compared With Varivax, When Given as a Second Dose to Healthy Children, 3 Months After the Administration of a First Dose at 12 to 15 Months of Age

This test checks whether GSK’s investigational chickenpox vaccine is safe and produces a strong immune response as the second dose when given to healthy children three months after their first dose at age 12–15 months.

Quick facts

• Phase: Phase 3
• Study type: Interventional
• Enrollment: 600 (estimated)
• Ages: 12 Months to 15 Months
• Sex: All
• Sponsor: GlaxoSmithKline (Industry-sponsored)
• Drugs / interventions: nirsevimab, immunotherapy, prednisone
• Locations: 3 sites (Salvaleón de Higüey, La Altagracia Province and 2 other locations)
• Trial ID: NCT06806137 on ClinicalTrials.gov

What this trial studies

The trial enrolls healthy children who have not had chickenpox or received a varicella vaccine and who received a first dose at 12–15 months. Participants receive either GSK’s investigational varicella vaccine or the licensed Varivax as their second dose three months after the first dose, with some children also receiving routine concomitant vaccines (MMR, hepatitis A, PCV13) per national schedule. Investigators will measure antibody responses and record safety data and adverse events following vaccination. The study is conducted at GSK investigational sites in the Dominican Republic.

Who should consider this trial

Good fit: Healthy children aged 12–15 months at first vaccination who have not previously had chickenpox or a varicella vaccine and whose caregivers can comply with study visits are ideal candidates.

Not a fit: Children who already had chickenpox, previously received a varicella vaccine, or have contraindications to live vaccines are unlikely to benefit from participating.

Why it matters

Potential benefit: If successful, this could provide an alternative second-dose varicella vaccine option with comparable protection and safety for toddlers.

How similar studies have performed: Two-dose schedules using licensed varicella vaccines like Varivax have been shown effective, so this trial tests whether the investigational vaccine matches that established standard.

Eligibility criteria

Inclusion Criteria:

* Participant's parent(s)/Legally acceptable representative (LAR)(s), who, in the opinion of the investigator, can and will comply with the requirements of the protocol
* 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 the first 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 study entry.

Exclusion Criteria:

* History of any reaction or hypersensitivity likely to be exacerbated by any component of the study interventions.
* Any confirmed or suspected immunosuppressive or immunodeficient condition, based on medical history and physical examination.
* Hypersensitivity to latex.
* Major congenital defects, as assessed by the investigator.
* Recurrent history of uncontrolled neurological disorders or seizures.
* History of varicella disease.
* Active untreated tuberculosis.
* Any other clinical condition that, in the opinion of the investigator, might pose additional risk to the participant due to participation in the study.
* 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 first dose of study interventions (Day -29 to Day 1), or their planned use during the study period.
* Planned administration of a vaccine in the period starting 30 days before the first dose and ending 43 days after the second dose of study interventions administration (Visit 3), with the exception of inactivated influenza vaccine which may be given at any time during the study and administered at a different location than the study interventions.
* 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:

    i) 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.

ii) 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 vaccinese.g., nirsevimab), antitumoral medication.
* Previous vaccination against measles, mumps, and rubella.
* Previous vaccination against hepatitis A virus.
* Previous vaccination against varicella 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.
* 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).
* Child in care.
* Any study personnel's immediate dependents, family, or household members.
* Participants with the following high-risk individuals in their household:

  i) Immunocompromised individuals. ii) Pregnant women without documented history of varicella. iii) Newborn infants of mothers without documented history of varicella. iv) Newborn infants born less than (\<) 28 weeks of gestation.

Where this trial is running

Salvaleón de Higüey, La Altagracia Province and 2 other locations

• GSK Investigational Site — Salvaleón de Higüey, La Altagracia Province, Dominican Republic (Recruiting)
• GSK Investigational Site — Constanza, Dominican Republic (Recruiting)
• GSK Investigational Site — Santo Domingo Oeste, Dominican Republic (Recruiting)

Study contacts

• Study coordinator: US GSK Clinical Trials Call Center

Conditions Chickenpox; Chicken pox; Investigational varicella vaccine Varicella; Varivax; Healthy Children