Seroprevalence of Neutralizing Antibodies Against Japanese Encephalitis Virus Among 6 Years Old Children With 5 Different Immunization Strategies in Zhejiang Province

Zhejiang Provincial Center for Disease Control and Prevention

Status and phase

Active, not recruiting

Phase 4

Conditions

Vaccine Preventable Disease

Japanese Encephalitis

Vaccine Reaction

Treatments

Biological: Japanese Encephalitis Vaccine (Vero Cell), Inactivated;

Other: No prospective interventions

Study type

Interventional

Funder types

Other

Industry

Identifiers

NCT04817917

ZJCDC20210317

Details and patient eligibility

About

This study is to evaluate the seroprevalence of neutralizing antibodies against Japanese encephalitis (JE) virus in children aged 6 years who were previously administered with 5 different immunization strategies by JE attenuated live vaccine (JEV-L) or/and inactivated vaccine (JEV-I). The secondary objective is to evaluate the immunogenicity of the booster dose of JEV-I at 6 years old for those previously immunized with 3 doses of JEV-I or those sequential administered with 1 dose of JEV-L and another dose of JEV-I.

Full description

Based on the retrospective registry in Zhejiang Provincial Immunization Information System, healthy children aged 6 years from 5 cohorts were included according to their previous immunization schedules on JE: 3 doses of JEV-I (Group 1), JEV-L+ JEV-I (Group 2), JEV-L+ JEV-I + JEV-I (Group 3), JEV-I + JEV-I+ JEV-L (Group 4), and 2 doses of JEV-L (Group 5). According to immunization programs in China, a booster dose of JEV-I is needed at the age of 6 for Group 1 and Group 2. A pre-vaccination blood sample (2.5ml) will be collected to evaluate the proportions of seropositivity before the booster dose of JEV-I. A second blood sample will be collected 28-35 days after the booster dose. Immunogenicity of the booster dose will be assessed by seroconversion rates, proportions of seropositivity and GMTs for these two groups. In addition, safety will be assessed with the occurrence of adverse events reported in these two groups. For the rest three groups who have completed the immunization schedules on JE, only one blood sample will be taken at the age of 6 to evaluate the proportions of seropositivity and GMTs after 4 years post the complete immunization schedules. Plague reduction neutralization test (PRNT) against both vaccine strains (SA-14-14-2 strain for JEV-L and Beijing P3 strain for JEV-I) will be used to test neutralizing antibody titers, so as to avoid potential bias in favor of either vaccine. PRNT50 titers (the reciprocal of the serum dilution that reduced the virus plaque count by 50% compared with the virus-only controls) ≥ 1:10 are deemed as positive.

Enrollment

712 patients

Sex

All

Ages

72 to 75 months old

Volunteers

Accepts Healthy Volunteers

Inclusion criteria

Participants aged ≥ 72 months to < 75 months.
Participants have completed routine immunization schedules in time.
Participants are healthy native residents.
Parents/guardians can understand the protocol requirements, provide informed consent, accept all scheduled visits, and comply with all trial procedures.

Exclusion criteria

History of neurological diseases or related symptoms.
An acute illness with fever (temperature ≥ 37.1℃) or any acute onset of chronic diseases.
Known impairment of immunologic function, or receipt of immunosuppressive therapy or immunoglobulin in the past 3 months.
Known allergy to any constituent of the vaccine.
Have been injected with other vaccines or any clinical trial drugs in the past 4 weeks.
Any condition which, in the opinion of the investigator, would pose a health risk to the subject or interfere with the vaccine.

Trial design

Primary purpose

Prevention

Allocation

Non-Randomized

Interventional model

Parallel Assignment

Masking

None (Open label)

712 participants in 5 patient groups

3JEV-I (Group 1)

Experimental group

Description:

Retrospective: 3 doses of JE vaccines. 2 doses of Inactivated JE Vaccine (JEV-I, 7-10 days apart) at 8 months of age and 1 dose of JEV-I at 2 years old. Prospective: 1 booster dose of JEV-I at 6 years old.

Treatment:

Biological: Japanese Encephalitis Vaccine (Vero Cell), Inactivated;

JEV-L+JEV-I (Group 2)

Experimental group

Description:

Retrospective: 2 doses of JE vaccines. 1 dose of JE attenuated live vaccine (JEV-L) at 8 months of age and 1 dose of JEV-I at 2 years old. Prospective: 1 booster dose of JEV-I at 6 years old.

Treatment:

Biological: Japanese Encephalitis Vaccine (Vero Cell), Inactivated;

JEV-L+2JEV-I (Group 3)

Experimental group

Description:

Retrospective: 3 doses of JE vaccines. 1 dose of JEV-L at 8 months of age and 2 dose (7-10 days apart) of JEV-I at 2 years old.

Treatment:

Other: No prospective interventions

2JEV-I+JEV-L (Group 4)

Experimental group

Description:

Retrospective: 3 doses of JE vaccines. 2 doses of JEV-I (7-10 days apart) at 8 months of age and 1 dose of JEV-L at 2 years old.