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.
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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
NONE
Enrollment
600
0.5ml for each dose, manufactured by Liaoning Chengda Biotechnology Co., Ltd., administered in the deltoid area of lateral arm by intramuscular injection.
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.
Jiashan County Center for Disease Control and Prevention
Jiaxing, Zhejiang, China
Pinghu Center For Disease Control and Prevention
Jiaxing, Zhejiang, China
Dongyang Center for Disease Control and Prevention
Jinhua, Zhejiang, China
Yongkang Center for Disease Control and Prevention
Jinhua, Zhejiang, China
Yuyao Center for Disease Control and Prevention
Ningbo, Zhejiang, China
Jiangshan Center For Disease Control and Prevention
Quzhou, Zhejiang, China
Percentage of Participants Testing Seropositive for Japanese Encephalitis Neutralizing Antibodies
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.
Time frame: 4 years after the booster vaccination at 24 months of age
Seroconversion Rates of Japanese Encephalitis Neutralizing Antibodies after Primary vaccination
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
Time frame: 30 days post-primary immunization
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
Percentage of Participants Testing Seropositive for Japanese Encephalitis Neutralizing Antibodies before and after 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.
Time frame: pre-primary immunization (Day 0) and 30 days post-primary immunization
Seroconversion Rates of Japanese Encephalitis Neutralizing Antibodies after Booster vaccination
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
Time frame: 30 days post-booster immunization
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
Percentage of Participants Testing Seropositive for Japanese Encephalitis Neutralizing Antibodies before and after 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.
Time frame: pre-booster immunization (Day 0) and 30 days post-booster immunization
Incidence of any Local and Systemic Adverse Events Within 30 Days of Each Vaccination
Adverse events will be collected through a combination of proactive visits by researchers and participant reports
Time frame: within 30 days of each vaccination
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