An Extension Study of EV-BR1701 Part A1

NCT07635966 | Completed

• 1 other identifier: EV-BR1701 Part A1 Extension
• Study Type: observational
• Target: 180
• Locations: 1 country
• Sites: 4

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.

Conditions

Enterovirus Infections

Outcome Measures

Primary Outcomes (3)

• The long-term immunogenicity of EnVAX-A71 on the seroconversion rate (SCR)

  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.

  From Sep-2025 to Dec-2025

• The long-term immunogenicity of EnVAX-A71 on SPR

  SPR (seroprotection rate, the proportion of the subjects with NTAb against EV71 titer ≥1:32)

  From Sep-2025 to Dec-2025

• The long-term immunogenicity of EnVAX-A71 on the geometric mean titer (GMT) and geometric mean titer ratio (GMTR) of EV71 neutralizing antibody (NTAb)

  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).

  From Sep-2025 to Dec-2025

Eligibility Criteria

• Age: 86 Months - 14 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Child (0-17)
• Sampling Method: Non-Probability Sample

Study Population

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.

You may qualify if:

• 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).
• The subject's guardian/legal representative is able and willing to comply with study procedures and provide signed informed consent.

You may not qualify if:

• History of bleeding disorder, hemostatic difficulties or significant bruising caused by phlebotomy since the last visit in EV-BR1701 main study.
• Having been vaccinated with any EV71 vaccine products.

Sponsors & Collaborators

• Enimmune Corporation: lead

Study Sites (4)

National Taiwan University Hospital HsinChu Branch

Hsinchu, Taiwan

Location

China Medical University Hospital

Taichung, Taiwan

Location

National Taiwan University Hospital

Taipei, Taiwan

Location

Linkou Chang Gung Memorial Hospital

Taoyuan, Taiwan

Location

MeSH Terms

Conditions

Enterovirus Infections

Condition Hierarchy (Ancestors)

Picornaviridae Infections; RNA Virus Infections; Virus Diseases; Infections

Study Officials

• Wendy Wu

  Enimmune Corporation

  STUDY DIRECTOR

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: PROSPECTIVE
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: May 28, 2026
• First Posted: June 9, 2026
• Study Start: September 20, 2025
• Primary Completion: December 27, 2025
• Study Completion: April 22, 2026
• Last Updated: June 10, 2026

Record last verified: 2026-06

Locations

TW (4)