Enterovirus Infections
Conditions
Brief summary
To determine the long-term immunogenicity more than 5 years after EnVAX-A71 vaccination in the pediatric population aged 2 months to \<6 years when first vaccinated.
Detailed description
I. Study Design: EV-BR1701 was a randomized, multi-nation, multi-centered, double-blinded, phase III study to evaluate the efficacy and safety of an EV71 vaccine, EnVAX-A71, in healthy infants and children in Taiwan (Part A) and Vietnam (Part B). In both Parts, a sub-study for immunogenicity assessment for up to one year was performed. This extension study of EV-BR1701 aims to evaluate the long-term immunogenicity persistence more than 5 years after EnVAX-A71 vaccination in subjects originally participating in the immunogenicity sub-study in Taiwan. The evaluable subjects of EV-BR1701 Part A1(immunogenicity sub-study), who were aged 2 months to \< 6 years when entering the main study and completed two injections of either EnVAX-A71 or placebo with evaluable data for the primary immunogenicity endpoint, will be recalled to enter this extension study for phlebotomy and immunogenicity analysis. These subjects will not receive further vaccination according to this extension study protocol. The principal investigators (PIs) and study coordinators (SCs) of the original medical center will contact the subject's guardians/legal representative by phone to return to the medical center for phlebotomy. Informed consent will be provided to the guardian/legal representative of the subjects, and the eligibility of subjects will be verified on the day of the recall visit. After the subject is evaluated by the PI and meets the phlebotomy requirements, the subject's guardian/legal representative will be asked to sign the informed consent form, and the subject will be given the same identifier as what he/she was originally assigned in the main study for continuity of his/her immunogenicity data. About 3-4 mL of blood will be collected from each subject, and the serum will be collected and sent to the designated central laboratory for testing. The validated neutralizing antibody (NTAb) analysis method will be used to determine the EV71-specific neutralizing antibody titer. The NTAb titer results will be directly sent to the CRO Data Management Team, and statistical analysis for immunogenicity will be performed and reported.
Interventions
None listed
Sponsors
Enimmune Corporation
Study design
Observational model
COHORT
Time perspective
PROSPECTIVE
Eligibility
Sex/Gender
ALL
Age
86 Months to 14 Years
Healthy volunteers
No
Inclusion criteria
1. Healthy children who were enrolled in Part A1 (immunogenicity sub-study) of EV-BR1701, received two injections of either EnVAX-A71 or placebo, and had blood sample collected on Day 56 for primary immunogenicity endpoint analysis (the "evaluable" subjects). 2. The subject's guardian/legal representative is able and willing to comply with study procedures and provide signed informed consent.
Exclusion criteria
1. History of bleeding disorder, hemostatic difficulties or significant bruising caused by phlebotomy since the last visit in EV-BR1701 main study. 2. Having been vaccinated with any EV71 vaccine products.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| The long-term immunogenicity of EnVAX-A71 on the seroconversion rate (SCR) | From Sep-2025 to Dec-2025 | SCR (seroconversion rate) is defined as the percentage of subjects achieving either a pre-vaccination neutralizing antibody titer \<1:8 and a post-vaccination neutralizing antibody titer ≥1:32, OR a pre-vaccination neutralizing antibody titer ≥1:8 and a minimum 4-fold increase in post-vaccination neutralizing antibody titer. |
| The long-term immunogenicity of EnVAX-A71 on SPR | From Sep-2025 to Dec-2025 | SPR (seroprotection rate, the proportion of the subjects with NTAb against EV71 titer ≥1:32) |
| The long-term immunogenicity of EnVAX-A71 on the geometric mean titer (GMT) and geometric mean titer ratio (GMTR) of EV71 neutralizing antibody (NTAb) | From Sep-2025 to Dec-2025 | GMTR (geometric mean titer ratio) is defined as the GMT at the recall visit divided by the GMT at pre-vaccination (Day 0 of main study). |
Countries
Taiwan
Contacts
STUDY_DIRECTORWendy Wu
Enimmune Corporation
Outcome results
None listed