Enterovirus InfectionsNCT07635966
An Extension Study of EV-BR1701 Part A1
An observational study of Enterovirus Infections, run by Enimmune Corporation at 4 sites in Taiwan.
Trial 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. Read more about this study
- Who is it for?
- Ages 86 months to 14 years
- Conditions the study is for
- Enterovirus Infections
- How many people
- 180 participants
- Where
- 4 sitesTaiwan
- Study dates
- 20 Sep 2025to 22 Apr 2026
- Phase
- Observational
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 86 months to 14 years
- All sexes
- No healthy volunteers
- Child
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.
Who may be able to join
- 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.
Who cannot join
- 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.
Trial locations and contacts
4 sites in 1 country.
Taiwan4 sites
National Taiwan University Hospital HsinChu Branch
Hsinchu
China Medical University Hospital
Taichung
National Taiwan University Hospital
Taipei
Linkou Chang Gung Memorial Hospital
Taoyuan
About this study
Official title: Long-Term Immunogenicity Study of an Adjuvanted Inactivated Enterovirus 71 (EV71) Vaccine in Healthy Infants and Children: An Extension Study of EV-BR1701 Part A1
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.
Read the detailed description
- 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.
- Conditions
- Enterovirus Infections
- Medical subject headings
- Enterovirus Infections
What is being measured
The primary outcome is the main question the study is designed to answer.
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.
Measured: 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)
Measured: 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).
Measured: From Sep-2025 to Dec-2025
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted9 Jun 2026
- Study start20 Sep 2025
- Primary completion27 Dec 2025
- Study completion22 Apr 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Enterovirus InfectionsStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 180 participants (actual)
Sponsor and investigators
- Lead sponsor
- Enimmune Corporation
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
- Investigators
- Wendy Wu, Study director, Enimmune Corporation
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07635966
- Sponsor's protocol ID
- EV-BR1701 Part A1 Extension
- Status last verified
- Jun 2026
- First submitted
- 28 May 2026
- Last updated
- 10 Jun 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided
Study at a glance
From the registry record, last updated by the sponsor on 10 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Long-Term Immunogenicity Study of an Adjuvanted Inactivated Enterovirus 71 (EV71) Vaccine in Healthy Infants and Children: An Extension Study of EV-BR1701 Part A1
- ClinicalTrials.gov ID
- NCT07635966
- Acronym / sponsor ID
- EV-BR1701 Part A1 Extension
- Conditions
- Enterovirus Infections
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 180 participants (actual)
- Lead sponsor
- Enimmune CorporationIndustry (pharma, biotech, devices)
- Study start
- 20 Sep 2025 (actual)
- Primary completion
- 27 Dec 2025 (actual)
- Study completion
- 22 Apr 2026 (actual)
- First posted
- 9 Jun 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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
- 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.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
Who may qualify
- Ages
- 86 months to 14 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child
- 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.
Key inclusion criteria (2 listed)
- 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.
Key exclusion criteria (2 listed)
- 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.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Primary outcome
The long-term immunogenicity of EnVAX-A71 on the seroconversion rate (SCR)
Time frame: 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
Time frame: 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)
Time frame: 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).
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 10 Jun 2026.
- Individual participant dataSharing planned: Undecided
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Wendy Wu study director
Enimmune Corporation
4 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Enterovirus Infections, run by Enimmune Corporation at 4 sites in Taiwan.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 2 inclusion and 2 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 10 Jun 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 4 sites in Taiwan. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
The long-term immunogenicity of EnVAX-A71 on the seroconversion rate (SCR) (time frame: From Sep-2025 to Dec-2025). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 10 Jun 2026.