Long-Term Immunogenicity of Envacgen® in Children
Extension Study of Protocol CT-EV-31s to Examine the Long-Term Immunogenicity After Receiving Inactivated EV71 Enterovirus Vaccine (Envacgen®) in Children
1 other identifier
observational
220
1 country
4
Brief 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.
Trial Health
Trial Health Score
Automated assessment based on enrollment pace, timeline, and geographic reach
participants targeted
Target at P75+ for all trials
Started Nov 2025
Shorter than P25 for all trials
4 active sites
Health score is calculated from publicly available data and should be used for screening purposes only.
Trial Relationships
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Study Timeline
Key milestones and dates
Study Start
First participant enrolled
November 24, 2025
CompletedPrimary Completion
Last participant's last visit for primary outcome
February 16, 2026
CompletedFirst Submitted
Initial submission to the registry
April 28, 2026
CompletedFirst Posted
Study publicly available on registry
May 5, 2026
CompletedStudy Completion
Last participant's last visit for all outcomes
July 31, 2026
ExpectedMay 5, 2026
April 1, 2026
3 months
April 28, 2026
April 28, 2026
Conditions
Keywords
Outcome Measures
Primary Outcomes (2)
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.
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.
Approximately 6 years after first dose of vaccination
Study Arms (2)
EV71 Vaccine with Adjuvant AlPO4
EV71 Vaccine Produced in Vero Cells with Adjuvant AlPO4
Adjuvant AlPO4
Placebo (Adjuvant AlPO4 only)
Interventions
EV71 vaccine with Adjuvant AlPO4 and the placebo (Adjuvant AlPO4 only) were randomly administrated to subject in CT-EV-31s study
Eligibility Criteria
Subjects who have completed participation in study CT-EV-31s.
You may qualify if:
- 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.
You may not qualify if:
- 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.
Contact the study team to confirm eligibility.
Sponsors & Collaborators
Study Sites (4)
Mackay Memorial Hospital, HsincChu
Hsinchu, Taiwan
Mackay Memorial Hospital, Taipei
Taipei, Taiwan
National Taiwan University Hospital
Taipei, Taiwan
Chang Gung Medical Hospital Linkou
Taoyuan, Taiwan
Biospecimen
Serum
Study Officials
- PRINCIPAL INVESTIGATOR
Li-Min Huang, M.D., Ph.D.
National Taiwan University Hospital
- PRINCIPAL INVESTIGATOR
Nan-Chang Chiu, M.D.
Mackay Memorial Hospital
- PRINCIPAL INVESTIGATOR
Cheng-Hsun Chiu, M.D., Ph.D.
Chang Gang Memorial Hospital, LinKou
- PRINCIPAL INVESTIGATOR
Chien-Yu Lin, M.D., Ph.D.
Mackay Memorial Hospital, HsinChu
Study Design
- Study Type
- observational
- Observational Model
- COHORT
- Time Perspective
- PROSPECTIVE
- Sponsor Type
- INDUSTRY
- Responsible Party
- SPONSOR
Study Record Dates
First Submitted
April 28, 2026
First Posted
May 5, 2026
Study Start
November 24, 2025
Primary Completion
February 16, 2026
Study Completion (Estimated)
July 31, 2026
Last Updated
May 5, 2026
Record last verified: 2026-04
Data Sharing
- IPD Sharing
- Will not share