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Safety and Immunogenicity of a Single Administration of Live-attenuated Japanese Encephalitis Vaccine in Previously Primed 2- to 5-year-olds and Naive 12- to 24-month-olds

2010; Lippincott Williams & Wilkins; Volume: 29; Issue: 12 Linguagem: Inglês

10.1097/inf.0b013e3181f68e9c

1532-0987

Kulkanya Chokephaibulkit, Chukiat Sirivichayakul, Usa Thisyakorn, Arunee Sabchareon, Chitsanu Pancharoen, Alain Bouckenooghe, Sophia Gailhardou, Mark Boaz, Emmanuel Feroldi,

Viral Infections and Outbreaks Research

Safe and effective Japanese encephalitis (JE) vaccines are needed to protect populations living in or visiting endemic areas. A live-attenuated JE-chimeric virus vaccine (JE-CV) has been developed with a single-dose regimen.In an open-label, crossover study, 100 children aged 2 to 5 years with a history of 2-dose primary vaccination with mouse-brain derived inactivated JE vaccine according to the Thai Expanded Program for Immunization schedule, and 200 JE vaccination-naive 12- to 24-month-old toddlers were randomized 1:1 to receive JE-CV, containing ≥4 log10 plaque forming units, 1 month before or after hepatitis A control vaccine. Neutralizing antibody titers were assessed using PRNT50 (titers expressed in inverse of dilution) before and 28 days after JE-CV, and at months 7 and 12.All 2- to 5-year-olds and 96% of 12- to 24-month-olds were seroprotected (titer ≥10) 28 days after JE-CV administration, and geometric mean titers (GMT) (95% confidence interval) in these age groups were 2634 (1928-3600) and 281 (219-362), respectively. One year later, seroprotection rates in the 2 age groups were 97% and 84% and GMTs were 454 and 62.3, respectively. Vaccine-induced antibodies neutralized a panel of wild-type JE isolates. There were no vaccine-related serious adverse events. Reactogenicity of JE-CV was comparable with that of the inactivated hepatitis A vaccine.A single administration of JE-CV has a good safety profile and elicits a protective immune response in both JE-naive toddlers and JE-primed young children.