Does the EV71 vaccine last? new study checks kids years later
NCT ID NCT07630493
First seen Jun 27, 2026 · Last updated Sep 11, 2026 · Updated 1 time
Summary
This study looks at whether an inactivated enterovirus 71 (EV71) vaccine still protects children two to two-and-a-half years after the last dose. It involves 126 healthy children from Vietnam who received the vaccine in an earlier phase 3 trial. Researchers will take a blood sample to measure neutralizing antibody levels, which indicate how well the immune system remembers the virus. No new vaccine is given in this extension study.
What this could mean
Our plain-language read of the trial. This is informational only, not medical advice or a prediction.
- Active substance
- EnVAX-A71 (inactivated enterovirus 71 vaccine with adjuvant)
- What this could lead to
- If successful, this could show that the EV71 vaccine provides long-lasting protection against hand, foot, and mouth disease caused by enterovirus 71.
- What could go wrong
- This is an extension study with no new vaccine doses given, so it only measures immune response over time. It does not test whether the vaccine still prevents infection, and the small sample size limits how much we can conclude.
This is an AI summary of the original study and may miss details. Read our disclaimer.
Study facts
What this study's own registry entry says, in plain language.
- Participants
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126 people
The number who actually took part.
- Started
-
Dec 2024
- Finished
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Sep 2025
- Lead sponsor
-
A company
The lead sponsor is a pharmaceutical, biotech, or medical-device company.
Who can take part
This study's own entry requirements. Only the study team can say for certain whether you qualify.
Who is studied
The main study is a randomized, multi-nation, multi-centered, double-blinded, phase III study on subjects aged 2 months to \<6 years old (\<72 months). Two parts are conducted in Taiwan (Group A) and Vietnam (Group B). This extended study involves the subjects enrolled in the EV-BR1701 Group B1 who received any IP injections. For Group B, out of 2727 subjects enrolled from June 2022 to Jul 2023, 241 subjects of Group B1 will be assigned to this extension study. The extension study aims to evaluate the immunogenicity persistence after EnVAX-A71 vaccination. The subjects of Group B1 will be recalled for phlebotomy and immunogenicity analysis. The subjects will not receive further study EV71 vaccines in the extension study.
- Ages
-
2 to 9 years
- Sex
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Anyone
- Healthy volunteers
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Not accepted
This study is not open to healthy volunteers. The entry requirements below say who it is open to.
Show the full entry requirements Hide the full entry requirements
Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.
Inclusion Criteria: 1. Healthy children enrolled in group B1 of the EV-BR1701 study who received at least one dose of IP injection with the duration after the last vaccination from at least 2 years up to 2 years and 6 months. 2. The subject's guardians are able and willing to comply with study procedures and provide signed informed consent. Exclusion Criteria: 1. Severe malnutrition or dysgenopathy at the screening visit. 2. Bleeding disorder diagnosed by a doctor or significant bruising or hemostatic difficulties with IM injections or phlebotomy. 3. Any condition in the investigator's opinion may interfere with evaluating study objectives.
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Conditions
The condition(s) this trial relates to.
As listed by the trial registrant
The condition terms exactly as the trial's registrant entered them.
Contacts and locations
Locations
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Centers for Disease Control and Prevention, Vinh Long Province, Vietnam
Vĩnh Long, Vinh Long Province, Vietnam
More trials for these conditions
Other studies related to the condition(s) this trial covers.