A Study to Evaluate the Immunogenicity and Safety of an EV71 Vaccine (Envacgen®) in Children Aged 6 to <10 Years Compared to Children Aged 2 to <6 Years

NCT07178522 | Active Not Recruiting Phase 3 DMC

• 1 other identifier: CT-EV-32
• Study Type: interventional
• Target: 378
• Locations: 1 country
• Sites: 3

Brief Summary

The purpose of this study is to assess the immunogenicity and safety of EV71 vaccine (Envacgen®) in Children Aged 6 to \<10 Years compared to Children Aged 2 to \<6 Years.

Conditions

Enterovirus 71 Inactivated Vaccine

Outcome Measures

Primary Outcomes (2)

• Immunogenicity of Envacgen®

  1. Geometric Mean Titer (GMT) of Neutralizing Antibody (NTAb) Measurement of NTAb titers against EV71 at 28 days after the second dose of Envacgen® in children aged 6 to \<10 years (Old group) compared with children aged 2 to \<6 years (Young group). 2. Seroresponse Rate (SRR) of Neutralizing Antibody (NTAb) Percentage of participants with seroresponse (defined as at least a four-fold increase from baseline in NTAb titers) at 28 days after the second dose of Envacgen® in children aged 6 to \<10 years (Old group) compared with children aged 2 to \<6 years (Young group).

  Day 1 to 28 days after the second vaccination.

• Incidence of Adverse Events(AEs) [Safety]

  Number and percentage of participants in the Old group (6 to \<10 years) and Young group (2 to \<6 years) with any reported adverse events within 28 days after vaccination with Envacgen®.

  Day 1 to 28 days after the second vaccination.

Secondary Outcomes (1)

• Incidence of Adverse Events(AEs) [Safety]

  Day 1 to 180 days after the second vaccination.

Other Outcomes (1)

• Immunogenicity of Envacgen® for cross-reaction

  Day 1 to 28 days after the second vaccination.

Study Arms (2)

Children Aged 6 to <10 Years

EXPERIMENTAL

EV71 Vaccine (Envacgen®)

Biological: Envacgen®

Children Aged 2 to <6 Years

ACTIVE COMPARATOR

EV71 Vaccine (Envacgen®)

Biological: Envacgen®

Interventions

Envacgen® BIOLOGICAL

Subjects are to receive a 0.5 mL IM injection of Envacgen®. Study drug is administered on Day 1 and Day 57 of the study.

Children Aged 2 to <6 Years; Children Aged 6 to <10 Years

Eligibility Criteria

• Age: 2 Years - 9 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Child (0-17)

You may qualify if:

• Healthy children aged 2 to \<10 years as established by medical history and clinical examination.
• Subject and/or the subject's parent/guardian is able to understand and sign the ICF.

You may not qualify if:

• Has poor venous access.
• Currently has a fever defined as ear/rectal temperature ≥ 38°C or axillary temperature ≥ 37.5 °C within 2 days before the time of planned vaccination.
• Has had previously known exposure to EV71 or has received EV71 vaccine.
• Has a history of herpangina or HFMD associated with enterovirus infection in the past 28 days before the date of planned study drug vaccination.
• Has been diagnosed with a significant neurological, pulmonary, cardiovascular, hematological, hepatic, or renal disorder.
• Has a history of hypersensitivity to vaccines, or a history of allergic disease or reactions likely to be exacerbated by any component or any residual trace components such as formaldehyde of the Envacgen® vaccine.
• Has used any investigational/nonregistered product (including drug, vaccine, or invasive medical device) within 28 days before study vaccination or plans to use any of them during the study period.
• Has confirmed or suspected autoimmune disorder or immunodeficiency.
• Has been administered or plans to be administered with any licensed live attenuated vaccine within 14 days before or after each study vaccination.
• Has used immunoglobulins via intravenous route or any blood products within 11 months before vaccination or plans to use any of them during the study period.
• Has received immunosuppressant, cytotoxic drug, corticosteroid (including prednisolone ≥ 0.5 mg/kg/day or equivalent), immunomodulator or acetylsalicylic acid for \> 14 days within 6 months before the first vaccination or plans to use any of them during the study period. (Inhaled and topical steroids are allowed).
• Has any medical or psychiatric condition that is a contraindication to protocol participation based on the judgment of the Investigator.

Sponsors & Collaborators

• Medigen Vaccine Biologics Corp.: lead

Study Sites (3)

National Taiwan University Hospital Hsin-Chu Branch

Hsinchu, Taiwan

Location

National Taiwan University Hospital

Taipei, Taiwan

Location

Chang Gung Medical Hospital Linkou

Taoyuan, Taiwan

Location

Study Design

• Study Type: interventional
• Phase: phase 3
• Allocation: NON RANDOMIZED
• Masking: NONE
• Purpose: PREVENTION
• Intervention Model: SINGLE GROUP
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: August 21, 2025
• First Posted: September 17, 2025
• Study Start: June 25, 2025
• Primary Completion (Estimated): July 31, 2026
• Study Completion (Estimated): October 31, 2026
• Last Updated: May 4, 2026

Record last verified: 2026-04

Data Sharing

• IPD Sharing: Will not share

Locations

TW (3)