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

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
Journal
Publication Sub Type
Journal Article, Original
Title
Pediatric Infectious Disease Journal
Frequency
Monthly
Publication Date
December 2016
Volume
Not applicable
Issue
Not applicable
Page(s)
Not applicable
LocationLocation CodeAvailable FormatAvailability
U.S. National Library of Medicine: PubMed/Medline Fulltext External Link (View)

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