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
The purpose of this study is to determine whether vYF (investigational vaccine) is safe and can help the body to develop antibodies (immunogenicity) compared with Stamaril vaccine and YF-VAX vaccine (both licensed vaccines) and when they are co-administered with Measles Mumps Rubella (MMR) vaccines in infants aged 11-15 months. Number of Participants: A total of 2440 participants is planned to be enrolled in VYF04 study. Study Arms and Duration: Eligible participants will be randomized in 2 independent groups (9-24 months, 2-5 years) to receive 1 dose of either vYF or Stamaril or YF-VAX in a 2:1:1 ratio within each age group. An additional group with participants of 11-15 months of age will also receive at the same vaccination visit vYF and a single dose of MMR vaccine. For the 2nd step (YF booster vaccine administration in a subset), at the Year (Y) 3 visit, a subset of 120 participants of the 9-24 months of age group who did receive a YF vaccine on Day(D) 01 will be invited to join a booster dose assessment (booster dose administered after the Y3 visit blood sample has been taken). Participants aged 11 to 15 months at the time of the concomitant administration of vYF and MMR will not be eligible for receiving a booster dose. The duration of each participation will be approximately 3 years for all participants (including participants co-administered on D01 with vYF and MMR), and 6 more months post-booster dose administration for the participants enrolled in the booster subset.
• 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)