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NCT Number: NCT06825312

Immunogenicity, Safety, and Antibody Persistence of Different Immunization Strategies Against Japanese Encephalitis

The main objective of this study is to evaluate the persistence of Japanese encephalitis antibodies in participants at the age of 6, after they have followed different Japanese encephalitis vaccination schedules. Furthermore, the study will assess the immunogenicity and antibody persistence of primary immunization across different Japanese encephalitis vaccination schedules, as well as the immunogenicity following booster immunizations within these schedules. The safety of each vaccine dose will also be evaluated.

Active, Not Recruiting

This study is active but is not currently recruiting participants.

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Key information

Conditions

Japanese Encephalitis Vaccine

Age range

8 month–8 month

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 4

Primary location

Jiashan County Center for Disease Control and Prevention, Jiaxing, Zhejiang, China

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About this study

This is a randomized, controlled, open-label, non-inferiority study. Healthy children aged 8 months will be invited to participate and randomly allocated to six groups (Group 1 to Group 6) in a 1:1:1:1:1:1 ratio. They will be administered the inactivated Japanese encephalitis vaccine (JEV-I) and/or the live attenuated Japanese encephalitis vaccine (JEV-L) based on the six schedules delineated in the protocol. The primary immunization will be administered to participants at 8 months of age, and a booster dose will be given at 24 months of age. Additionally, participants in Groups 1, 2, and 5 will receive an additional booster dose at the age of 6.

Blood samples (3 mL) will be collected from participants at 8 months, 24 months, and 6 years of age. Samples will be taken before vaccination and 30 days after it for detecting Japanese encephalitis neutralizing antibodies. The titers of these antibodies will be assayed via the 50% plaque reduction neutralization test. Those in groups 3, 4, and 6 who've completed all immunization procedures by 24 months old will have a blood sample taken at 6 years old.

Who can participate

Healthy volunteers accepted: Yes

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

Inclusion criteria

  • Healthy children aged 8 months who are permanent residents of the study area.
  • Legal guardians can understand the requirements and processes of the study, provide written informed consent, and comply with all procedures as required by the clinical research protocol.
  • Able to receive the full course of Japanese encephalitis vaccinations according to the immunization strategy in the research protocol, including receiving the primary immunization at 8 months of age and the booster immunizations at 24 months of age and 6 years of age.

Exclusion criteria

  • Unable to finish the full course of primary and booster immunizations at the study area, and unable to fulfill the follow-up visits prescribed in the protocol.
  • Non-compliance with the vaccination strategy for each group, as stated in the protocol, regarding Japanese encephalitis vaccines with proper doses and varieties.
  • Allergic to any component of the study vaccine or having a history of allergic reactions to any vaccines.
  • Having a history of symptoms or signs of neurological diseases or other contraindications for Japanese encephalitis vaccine vaccination.
  • Having used immunosuppressants or blood products following birth.
  • Receiving other vaccines simultaneously while receiving the Japanese encephalitis vaccine of this project.
  • Any conditions that may interfere with the evaluation of the study, as deemed by the researcher.

Treatment and study plan

Japanese Encephalitis Vaccine (Vero Cell), Inactivated

Biological

0.5ml for each dose, manufactured by Liaoning Chengda Biotechnology Co., Ltd., administered in the deltoid area of lateral arm by intramuscular injection.

Japanese Encephalitis Vaccine, Live

Biological

0.5ml for each dose, manufactured by Chengdu Institute of Biological Products Co., Ltd., administered subcutaneously in the lower part of the deltoid area of lateral arm.

Primary outcomes

  1. Percentage of Participants Testing Seropositive for Japanese Encephalitis Neutralizing Antibodies

    Time frame: 4 years after the booster vaccination at 24 months of age

    The persistence of immunity following various Japanese encephalitis (JE) vaccination schedules is evaluated based on the proportion of participants exhibiting seropositivity for JE neutralizing antibodies at 6 years of age. Seropositivity is defined as a JE neutralizing antibody titer of at least 1:10, as ascertained by the 50% plaque reduction neutralization test.

Secondary outcomes

  1. Seroconversion Rates of Japanese Encephalitis Neutralizing Antibodies after Primary vaccination

    Time frame: 30 days post-primary immunization

    The seroconversion rate is defined as the percentage of participants with a change in Japanese Encephalitis neutralizing antibody titer from <1:10 at baseline (pre-vaccination) to a titer of ≥1:10 30 days post-vaccination, or a 4-fold or greater rise from the baseline, as measured by the 50% plaque reduction neutralization test

  2. Geometric Mean Titer of Japanese Encephalitis Neutralizing Antibodies before and after Primary Immunization

    Time frame: pre-primary immunization (Day 0) and 30 days post-primary immunization

  3. Percentage of Participants Testing Seropositive for Japanese Encephalitis Neutralizing Antibodies before and after Primary Immunization

    Time frame: pre-primary immunization (Day 0) and 30 days post-primary immunization

    Seropositivity is defined as a Japanese Encephalitis neutralizing antibody titer of at least 1:10, as ascertained by the 50% plaque reduction neutralization test.

  4. Seroconversion Rates of Japanese Encephalitis Neutralizing Antibodies after Booster vaccination

    Time frame: 30 days post-booster immunization

    The seroconversion rate is defined as the percentage of participants with a change in Japanese Encephalitis neutralizing antibody titer from <1:10 at baseline (pre-vaccination) to a titer of ≥1:10 30 days post-vaccination, or a 4-fold or greater rise from the baseline, as measured by the 50% plaque reduction neutralization test

  5. Geometric Mean Titer of Japanese Encephalitis Neutralizing Antibodies before and after booster Immunization

    Time frame: pre-booster immunization (Day 0) and 30 days post-booster immunization

  6. Percentage of Participants Testing Seropositive for Japanese Encephalitis Neutralizing Antibodies before and after booster Immunization

    Time frame: pre-booster immunization (Day 0) and 30 days post-booster immunization

    Seropositivity is defined as a Japanese Encephalitis neutralizing antibody titer of at least 1:10, as ascertained by the 50% plaque reduction neutralization test.

  7. Incidence of any Local and Systemic Adverse Events Within 30 Days of Each Vaccination

    Time frame: within 30 days of each vaccination

    Adverse events will be collected through a combination of proactive visits by researchers and participant reports

Sponsors and collaborators

Lead sponsor

Liaoning Chengda Biotechnology CO., LTD

Industry

Collaborators

  • Zhejiang Provincial Center for Disease Control and Prevention

Registry information

Important dates

Study start
2023
Primary completion
2030
Study completion
2031
First posted
Feb 13, 2025
Registry last updated
Mar 11, 2025

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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