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NCT Number: NCT07568522

Long-Term Immunogenicity of 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.

Active, Not Recruiting

This study is active but is not currently recruiting participants.

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Key information

Conditions

Enterovirus 71 Human

Age range

6 year–13 year

Sex eligibility

All sexes

Study type

Observational

Primary location

Mackay Memorial Hospital, HsincChu, Hsinchu, Taiwan

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About this study

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.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • 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.

Exclusion criteria

  • 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.

Treatment and study plan

EV71 vaccine

Biological

EV71 vaccine with Adjuvant AlPO4 and the placebo (Adjuvant AlPO4 only) were randomly administrated to subject in CT-EV-31s study

Primary outcomes

  1. 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.

  2. 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.

Sponsors and collaborators

Lead sponsor

Medigen Vaccine Biologics Corp.

Industry

Registry information

Official study title

Extension Study of Protocol CT-EV-31s to Examine the Long-Term Immunogenicity After Receiving Inactivated EV71 Enterovirus Vaccine (Envacgen®) in Children

Important dates

Study start
2025
Primary completion
2026
Study completion
2026
First posted
May 5, 2026
Registry last updated
May 5, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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