title: Long term immunity to live attenuated Japanese encephalitis chimeric virus vaccine: randomized, double-blind, 5-year phase II study in healthy adults.
abstract: In a randomized, double-blind study, 202 healthy adults were randomized to receive a live, attenuated Japanese encephalitis chimeric virus vaccine (JE-CV) and placebo 28 days apart in a cross-over design. A subgroup of 98 volunteers received a JE-CV booster at month 6. Safety, immunogenicity, and persistence of antibodies to month 60 were evaluated. There were no unexpected adverse events (AEs) and the incidence of AEs between JE-CV and placebo were similar. There were three serious adverse events (SAE) and no deaths. A moderately severe case of acute viral illness commencing 39 days after placebo administration was the only SAE considered possibly related to immunization. 99% of vaccine recipients achieved a seroprotective antibody titer ≥ 10 to JE-CV 28 days following the single dose of JE-CV, and 97% were seroprotected at month 6. Kaplan Meier analysis showed that after a single dose of JE-CV, 87% of the participants who were seroprotected at month 6 were still protected at month 60. This rate was 96% among those who received a booster immunization at month 6. 95% of subjects developed a neutralizing titer ≥ 10 against at least three of the four strains of a panel of wild-type Japanese encephalitis virus (JEV) strains on day 28 after immunization. At month 60, that proportion was 65% for participants who received a single dose of JE-CV and 75% for the booster group. These results suggest that JE-CV is safe, well tolerated and that a single dose provides long-lasting immunity to wild-type strains.
authors.affiliation: Australian Army Malaria Institute, Queensland, Australia.
authors.forename: Peter E
authors.initials: PE
authors.lastname: Nasveld
authors.forename: Andrew
authors.initials: A
authors.lastname: Ebringer
authors.forename: Nathan
authors.initials: N
authors.lastname: Elmes
authors.forename: Sonya
authors.initials: S
authors.lastname: Bennett
authors.forename: Sutee
authors.initials: S
authors.lastname: Yoksan
authors.forename: John
authors.initials: J
authors.lastname: Aaskov
authors.forename: Karen
authors.initials: K
authors.lastname: McCarthy
authors.forename: Niranjan
authors.initials: N
authors.lastname: Kanesa-thasan
authors.forename: Claude
authors.initials: C
authors.lastname: Meric
authors.forename: Mark
authors.initials: M
authors.lastname: Reid
mesh_terms: D000293:Adolescent; D000328:Adult; D000914:Antibodies, Viral / Q000097:blood; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004672:Encephalitis, Japanese / Q000517:prevention & control; D005260:Female; D006805:Human Experimentation; D006801:Humans; D007117:Immunization, Secondary / Q000379:methods; D022321:Japanese Encephalitis Vaccines / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D010919:Placebos / Q000008:administration & dosage; D013997:Time Factors; D014611:Vaccination / Q000379:methods; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology; D055815:Young Adult
chemical_list: D000914:Antibodies, Viral; D022321:Japanese Encephalitis Vaccines; D010919:Placebos; D014613:Vaccines, Attenuated