Long Term Persistence and Effect of a Booster Dose of the Japanese Encephalitis Vaccine IC51

Valneva Austria GmbH349 enrolled

Overview

The study investigates the long term persistence the Japanese encephalitis vaccine IC51 and the need of a booster dose

This is an open label, non-randomized multi-center phase 3 follow-up study. All volunteers having completed trial IC51-304 (NCT00595790) will be enrolled into this trial at 2 sites

Study Type

INTERVENTIONAL

Allocation

Purpose

PREVENTION

Masking

NONE

Enrollment

349

Conditions

Japanese Encephalitis

Interventions

IC51BIOLOGICAL

Eligibility

Sex: ALLMin age: 18 YearsHealthy volunteers:

Medical Language ↔ Plain English

Inclusion Criteria: * At least 18 years of age * Written informed consent obtained prior to study entry * Subjects correctly included in and having completed study IC51-304 according to the protocol. Exclusion Criteria: * Use of any other investigational or non-registered drug or vaccine in addition to the study vaccine during the study period * Immunodeficiency including post-organ-transplantation or immunosuppressive therapy * Pregnancy, lactation or unreliable contraception in female subjects

Outcomes

Primary Outcomes

Long Term Immunogenicity of IC51 Vaccine 24 Months After the Primary Vaccination

Seroprotection rate (SPR) (anti-JEV neutralizing antibody titer ≥ 1:10) 24 months (M24) after the primary vaccination - imputed; Persistence of immunogenicity (SPR) at M24 defined as: * pos. (positive) (persistent): Subjects * with a non-missing, pos. seroconversion at D56 (Study IC51-304) and * without booster at M11 or M23 and * with non-missing, seroprotection (SP) pos. PRNT50 at M6 or M12 and * with non-missing, SP pos. PRNT50 at M24 * neg. (negative) (non-persistent): Subjects with * missing or neg. seroconversion at D56 (Study IC51-304) or * booster at M11 or at M23, or * non-missing, SP neg. PRNT50 at M6 or M12 or * missing PRNT50 at both M6 and M12 or * missing or SP neg. PRNT50 (serum dilution giving 50% reduction in plaques in a Plaque Reduction Neutralization Test) at M24

Time frame: - 24 months

Secondary Outcomes

SPR 24 Months After the Primary Vaccination (Observed)

Persistence of immunogenicity (SPR) at M24 (observed) defined as : * positive (persistent): Subjects * with a non-missing, positive seroconversion at D56 (Study IC51-304), and * who did not receive a booster dose at Visit 2 (M11) or Visit 4 (M23), and * with a non-missing, SP positive PRNT50 result at Visit 1 (M6) or Visit 3 (M12), and * with a non-missing, SP positive PRNT50 result at Visit 5 (M24) * negative (non-persistent): Subjects * with missing or negative seroconversion at D56 (Study IC51-304), or * who did receive a booster dose at Visit 2 (M11) or at Visit 4 (M23), or * with a non-missing, SP negative PRNT50 result at Visit 1 (M6) or Visit 3 (M12), or * with a missing PRNT50 result at both Visit 1 (M6) and Visit 3 (M12), or * with a non-missing, SP negative PRNT50 result at Visit 5 (M24)

Time frame: 24 months

Persistent and Actual SPR 6, 12 and 24 Months After Primary Vaccination

Time frame: - 24 months

Persistent and Actual GMT 6, 12 and 24 Months After Primary Vaccination

Time frame: 24 months

Data from ClinicalTrials.gov

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