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HERDIN Record #: PCHRD17021916082282 Submitted: 20 February 2017 Modified: 03 March 2017

Long-term immunogenicity of a single dose of Japanese encephalitis chimeric virus vaccine in toddlers and booster response 5 years after primary immunization.

Pope Kosalaraksa ,
Veerachai Watanaveeradej ,
Chitansu  Pancharoen ,
Alain Bouckenooghe,
Emmanuel  Feroldi,
Maria Rosario Capeding

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BACKGROUND: Japanese encephalitis (JE) is an important mosquito-borne viral disease that is endemic in Asia, Western Pacific countries, and Northern Australia. Although there is no antiviral treatment, vaccination is effective in preventing this disease.
METHODS: We followed a cohort of 596 children for 5 years after primary vaccination at 12-18 months of age with JE chimeric virus vaccine (JE-CV; IMOJEV) in a multicenter, phase III trial in Thailand and the Philippines to assess antibody persistence and safety. At the end of the 5 years, a subgroup of 85 participants, at one site in Thailand, was followed after administration of a JE-CV booster vaccination. JE antibody titers were measured annually after primary vaccination and 28 days after booster vaccination using a 50% plaque reduction neutralization test (PRNT50). Seroprotection was defined as a JE-CV neutralizing antibody titer ≥10 (1/dil). Kaplan-Meier survival analysis was used to estimate the proportion of participants maintaining protective JE-CV neutralizing antibody titers.
RESULTS: At 1, 2, 3, 4 and 5 years after vaccination with JE-CV, 88.5%, 82.9%, 78.2%, 74.0% and 68.6% of the participants followed remained seroprotected. GMTs in the subgroup assessed after receipt of a booster dose increased from 61.2 (95% CI; 43.8-85.7) pre-booster to 4951 (95% CI; 3928-6241) 28 days post-booster, with all participants seroprotected. There were no safety concerns identified.
CONCLUSIONS: Protective immune responses persisted for at least 5 years after a JE-CV primary immunization in the majority of participants. JE-CV booster induced a robust immune response even after a 5-year interval.

Publication Type
Publication Sub Type
Journal Article, Original
Pediatric Infectious Disease Journal
Publication Date
December 2016
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U.S. National Library of Medicine: PubMed/Medline Fulltext External Link (View)

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