Phase III comparison of vYF, Stamaril and YF-VAX in children aged 9 months to 5 years

A Parallel Group, Phase III Randomized, Modified Double-blind, Active Controlled Study to Investigate the Immunogenicity and Safety of vYF Compared to Licensed YF Vaccines in Pediatric Population Aged 9 Months to 5 Years of Age

This study tests whether the investigational vYF vaccine is safe and produces protective antibodies in infants and young children compared with licensed Stamaril or YF-VAX vaccines, including when given with the MMR vaccine.

Quick facts

• Phase: Phase 3
• Study type: Interventional
• Enrollment: 2440 (estimated)
• Ages: 9 Months to 5 Years
• Sex: All
• Sponsor: Sanofi (Industry-sponsored)
• Drugs / interventions: chemotherapy, prednisone
• Locations: 13 sites (San Pedro Sula and 12 other locations)
• Trial ID: NCT07103148 on ClinicalTrials.gov

What this trial studies

This randomized Phase III trial enrolls children 9 months to 5 years into age-stratified groups (9–24 months and 2–5 years) and randomizes them 2:1:1 to receive vYF, Stamaril, or YF-VAX. A separate co-administration group of 11–15 month-olds will receive vYF together with a single dose of MMR to evaluate concurrent immunization. Participants are followed for approximately 3 years for safety and antibody responses, with a subset invited for a YF booster at Year 3. The study is sponsored by Sanofi and is the first pediatric Phase III evaluation of the investigational vYF vaccine.

Who should consider this trial

Good fit: Healthy infants and children aged 9 months to 5 years — including a co-administration subgroup aged 11–15 months and medically stable premature infants born at 27–36 weeks — are the intended participants.

Not a fit: Children with significant medical problems, immunodeficiency, or those outside the 9 months–5 years age range are unlikely to be eligible or to benefit from participation.

Why it matters

Potential benefit: If successful, vYF could become an additional safe and effective yellow fever vaccine option for infants and young children and support coadministration with routine MMR immunization.

How similar studies have performed: Licensed yellow fever vaccines like Stamaril and YF-VAX have a long-established record of protective antibody responses, but vYF is a new formulation and this is its first pediatric Phase III evaluation.

Eligibility criteria

Inclusion Criteria:

* Aged 9 months to 5 years on the day of inclusion\*

  \* "9 months to 5 years" means from the day of the 9th month after birth to the day before the 6th year birthday
* Aged 11 to 15 months\* on the day of inclusion for participants enrolled in the MMR co-administration group

  \* "11 to 15 months" means from the day of the 11th month after birth to the day before the 16th month birthday
* Participants who are healthy as determined by medical evaluation including medical history and physical examination
* For infants\*, born after a gestation period of 27 through 36 weeks and medically stable as assessed by the investigator, based on the following definition: "Medically stable" refers to the condition of premature infants who do not require significant medical support or ongoing management for debilitating disease and who have demonstrated a clinical course of sustained recovery by the time they receive the first dose of study intervention

  \* Infants aged 9 months to 11 months up to the day before the 12th month birthday
* Participant and parent/LAR are able to attend all scheduled visits and to comply with all study procedures
* ICF has been signed and dated by the parent(s) or other LAR (and by an independent witness if required by local regulations)

Exclusion Criteria:

Participants are excluded from the study if any of the following criteria apply:

* Known or suspected congenital or acquired immunodeficiency; or receipt of immunosuppressive therapy, such as anti-cancer chemotherapy irradiation therapy, within the preceding 6 months; or long-term systemic corticosteroid therapy (prednisone or equivalent for more than 2 consecutive weeks within the past 3 months)
* Known history of FV infection
* Known systemic hypersensitivity to any of the study intervention components, eggs or history of a life-threatening reaction to the study interventions used in the study or to a product containing any of the same substances
* Moderate or severe acute illness/infection (according to Investigator judgment) or febrile illness (temperature ≥ 38.0°C \[≥ 100.4°F\]) on the day of study intervention administration. A prospective participant should not be included in the study until the condition has resolved or the febrile event has subsided.
* Chronic illness\* that, in the opinion of the Investigator, is at a stage where it might interfere with study conduct or completion , including malignancy, such as leukemia, or lymphoma

  \*Chronic illness may include, but is not limited to, cardiac disorders, renal disorders, auto-immune disorders, diabetes, psychiatric disorders or chronic infection
* History of central nervous system disorder or disease, including seizures and febrile seizures
* Receipt of any vaccine in the 4 weeks preceding the study intervention administration or planned receipt of any vaccine in the 4 weeks following the study intervention administration. Vaccine to be administered as part of the National Immunization Schedule will be postponed after the D29 visit
* Previous vaccination against a FV disease at any time including YF with an investigational or marketed vaccine
* Receipt of immune globulins, blood or blood-derived products in the past 6 months
* Administration of any anti-viral within 2 months preceding the study intervention administration and up to the 6 weeks following the study intervention administration
* For participants enrolled in the MMR co-administration group: previous vaccination against measles, measles/mumps/rubella
* For participants enrolled in the MMR co-administration group: history of measles, mumps, rubella confirmed either clinically, serologically, or microbiologically
* Known history or laboratory evidence of HIV infection
* Known history of hepatitis B or hepatitis C seropositivity
* Personal or family history of thymic pathology (thymoma, thymectomy, or myasthenia)
* Participation at the time of study enrollment (or in the 4 weeks preceding the study intervention administration) or planned participation during the first year of the 3-year follow-up in another clinical study investigating a vaccine, drug, medical device, or medical procedure. Enrollment in another study after the first 6 months of follow-up is permitted, assuming it does not exclude participation in this study.
* In an emergency setting, or hospitalized involuntary
* Identified as a natural or adopted child of the Investigator or employee with direct involvement in the proposed study

Where this trial is running

San Pedro Sula and 12 other locations

• Investigational Site Number : 3400001 — San Pedro Sula, Honduras (Recruiting)
• Investigational Site Number : 3400005 — San Pedro Sula, Cortes, Honduras (Recruiting)
• Investigational Site Number : 3400002 — Tegucigalpa, Honduras (Recruiting)
• Investigational Site Number : 3400003 — Tegucigalpa, Honduras (Recruiting)
• Investigational Site Number : 3400007 — Tegucigalpa, Honduras (Recruiting)
• Investigational Site Number : 4840007 — Torreón, Coahuila, Mexico (Recruiting)
• Investigational Site Number : 4840013 — Cuernavaca, Morelos, Mexico (Recruiting)
• Investigational Site Number : 4840015 — Tizimín, Yucatán, Mexico (Recruiting)
• Investigational Site Number : 4840009 — Chihuahua City, Mexico (Recruiting)
• Investigational Site Number : 4840005 — Ecatepec de Morelos, Mexico (Recruiting)
• Investigational Site Number : 5910001 — Panama City, Panama (Recruiting)
• Investigational Site Number : 5910002 — Panama City, Panama (Recruiting)
• Investigational Site Number : 5910003 — Panama City, Panama (Recruiting)

Study contacts

• Study coordinator: Trial Transparency email recommended (Toll free for US & Canada)

Conditions Yellow Fever Immunization; Yellow fever