Enterovirus 71 HumanNCT07568522
Long-Term Immunogenicity of Envacgen® in Children
An observational study of Enterovirus 71 Human, run by Medigen Vaccine Biologics Corp. at 4 sites in Taiwan.
Trial summary
This study is designed to evaluate the long-term antibody titers of Envacgen® approximately 6 years after the first vaccination dose in participants who were aged 2 months to <6 years at the time of enrollment in the CT-EV-31s study. Read more about this study
- Who is it for?
- Ages 6 to 13 yearsHealthy volunteers can take part
- Conditions the study is for
- Enterovirus 71 Human
- What is being tested?
- EV71 vaccine
- Type of treatment
- Vaccines
- How many people
- 220 participants
- Where
- 4 sitesTaiwan
- Study dates
- 24 Nov 2025to 26 Jun 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 6 to 13 years
- All sexes
- Healthy volunteers accepted
- Child
Study population: Subjects who have completed participation in study CT-EV-31s.
Who may be able to join
- Participants who have completed participation in study CT-EV-31s and have received protocol specified doses of EV71 vaccine or Placebo.
- The participant and/or participant's parent/guardian is able to understand and sign the informed consent form.
Who cannot join
- The participant and/or participant's parent/guardian refuse to comply with the study procedures.
- After completing the CT-EV-31s trial, participants who received any EV71 vaccine before participating in this study.
Trial locations and contacts
4 sites in 1 country.
Taiwan4 sites
Mackay Memorial Hospital, HsincChu
Hsinchu
Mackay Memorial Hospital, Taipei
Taipei
National Taiwan University Hospital
Taipei
Chang Gung Medical Hospital Linkou
Taoyuan
About this study
Official title: Extension Study of Protocol CT-EV-31s to Examine the Long-Term Immunogenicity After Receiving Inactivated EV71 Enterovirus Vaccine (Envacgen®) in Children
This study is designed to evaluate the long-term antibody titers of Envacgen® approximately 6 years after the first vaccination dose in participants who were aged 2 months to <6 years at the time of enrollment in the CT-EV-31s study.
Read the detailed description
This is an extension study of protocol CT-EV-31s, to evaluate the long-term immunogenicity of EV71 Enterovirus Vaccine (Envacgen®).
The study will consist of a single visit approximately 6 years after the first vaccination of the EV71 vaccine or Placebo in participants aged 2 months to < 6 years when participating in the CT-EV-31s study. Immunogenicity response against EV71 virus antigen at the visit will be assessed.
- Conditions
- Enterovirus 71 Human
- Being tested
- EV71 vaccine
- Keywords
- EV71 vaccine, Envacgen®
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
EV71 vaccineBiological
EV71 vaccine with Adjuvant AlPO4 and the placebo (Adjuvant AlPO4 only) were randomly administrated to subject in CT-EV-31s study
| Study group | Role | What they receive |
|---|---|---|
| EV71 Vaccine with Adjuvant AlPO4 | EV71 Vaccine Produced in Vero Cells with Adjuvant AlPO4 Receives: Biological: EV71 vaccine | |
| Adjuvant AlPO4 | Placebo (Adjuvant AlPO4 only) Receives: Biological: EV71 vaccine |
What is being measured
The primary outcome is the main question the study is designed to answer.
Serum neutralizing antibody titer
Geometric mean titer (GMT) of EV71 neutralizing antibody at approximately 6 years after first dose of EV71 vaccination or Placebo for participants.
Measured: Approximately 6 years after first dose of vaccination.
Seroprotection rate
Seroprotection rate (defined as neutralizing antibody titer ≥1:32) at approximately 6 years after first dose of EV71 vaccination or Placebo for participants.
Measured: Approximately 6 years after first dose of vaccination
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted5 May 2026
- Study start24 Nov 2025
- Primary completion16 Feb 2026
- Study completion26 Jun 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Enterovirus 71 HumanStudies 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
- 220 participants (actual)
Sponsor and investigators
- Lead sponsor
- Medigen Vaccine Biologics Corp.
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
- Investigators
- Li-Min Huang, M.D., Ph.D., Principal investigator, National Taiwan University HospitalNan-Chang Chiu, M.D., Principal investigator, Mackay Memorial HospitalCheng-Hsun Chiu, M.D., Ph.D., Principal investigator, Chang Gang Memorial Hospital, LinKouChien-Yu Lin, M.D., Ph.D., Principal investigator, Mackay Memorial Hospital, HsinChu
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07568522
- Sponsor's protocol ID
- FU-EV-31
- Status last verified
- Apr 2026
- First submitted
- 28 Apr 2026
- Last updated
- 7 Oct 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 7 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Extension Study of Protocol CT-EV-31s to Examine the Long-Term Immunogenicity After Receiving Inactivated EV71 Enterovirus Vaccine (Envacgen®) in Children
- ClinicalTrials.gov ID
- NCT07568522
- Acronym / sponsor ID
- FU-EV-31
- Conditions
- Enterovirus 71 Human
- Keywords
- EV71 vaccine, Envacgen®
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 220 participants (actual)
- Lead sponsor
- Medigen Vaccine Biologics Corp.Industry (pharma, biotech, devices)
- Study start
- 24 Nov 2025 (actual)
- Primary completion
- 16 Feb 2026 (actual)
- Study completion
- 26 Jun 2026 (actual)
- First posted
- 5 May 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.
This study is designed to evaluate the long-term antibody titers of Envacgen® approximately 6 years after the first vaccination dose in participants who were aged 2 months to <6 years at the time of enrollment in the CT-EV-31s study.
Detailed description
This is an extension study of protocol CT-EV-31s, to evaluate the long-term immunogenicity of EV71 Enterovirus Vaccine (Envacgen®).
The study will consist of a single visit approximately 6 years after the first vaccination of the EV71 vaccine or Placebo in participants aged 2 months to < 6 years when participating in the CT-EV-31s study. Immunogenicity response against EV71 virus antigen at the visit will be assessed.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| EV71 Vaccine with Adjuvant AlPO4 | – | Biological: EV71 vaccineEV71 Vaccine Produced in Vero Cells with Adjuvant AlPO4 |
| Adjuvant AlPO4 | – | Biological: EV71 vaccinePlacebo (Adjuvant AlPO4 only) |
Who may qualify
- Ages
- 6 to 13 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Child
- Study population
- Subjects who have completed participation in study CT-EV-31s.
Key inclusion criteria (2 listed)
- Participants who have completed participation in study CT-EV-31s and have received protocol specified doses of EV71 vaccine or Placebo.
- The participant and/or participant's parent/guardian is able to understand and sign the informed consent form.
Key exclusion criteria (2 listed)
- The participant and/or participant's parent/guardian refuse to comply with the study procedures.
- After completing the CT-EV-31s trial, participants who received any EV71 vaccine before participating in this study.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| EV71 vaccineEV71 vaccine with Adjuvant AlPO4 and the placebo (Adjuvant AlPO4 only) were randomly administrated to subject in CT-EV-31s study | Biological | Adjuvant AlPO4, EV71 Vaccine with Adjuvant AlPO4 |
Primary outcome
Serum neutralizing antibody titer
Time frame: Approximately 6 years after first dose of vaccination.
Geometric mean titer (GMT) of EV71 neutralizing antibody at approximately 6 years after first dose of EV71 vaccination or Placebo for participants.
Seroprotection rate
Time frame: Approximately 6 years after first dose of vaccination
Seroprotection rate (defined as neutralizing antibody titer ≥1:32) at approximately 6 years after first dose of EV71 vaccination or Placebo for participants.
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 7 Oct 2026.
- Individual participant dataSharing planned: No
Related trials for Enterovirus 71 Human
Enrolling by invitationObservational study
Study on the Persistence of Immunity Following EV71 Vaccination
Hand, Foot, and Mouth Disease, Hand, Foot, and Mouth Disease (HFMD)
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.
Li-Min Huang, M.D., Ph.D. principal investigator
National Taiwan University Hospital
Nan-Chang Chiu, M.D. principal investigator
Mackay Memorial Hospital
Cheng-Hsun Chiu, M.D., Ph.D. principal investigator
Chang Gang Memorial Hospital, LinKou
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 71 Human, run by Medigen Vaccine Biologics Corp. 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 7 Oct 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?
Serum neutralizing antibody titer (time frame: Approximately 6 years after first dose of vaccination.). The study lists 2 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 7 Oct 2026.