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: multicenter randomized controlled trial.

Abstract

BACKGROUND:

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.

METHODS:

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.

RESULTS:

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.

CONCLUSIONS:

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.

• Authors: Kulkanya Chokephaibulkit, Chukiat Sirivichayakul, Usa Thisyakorn, Arunee Sabchareon, Chitsanu Pancharoen, Alain Bouckenooghe, Sophia Gailhardou, Mark Boaz, Emmanuel Feroldi
• Journal: The Pediatric infectious disease journal (Pediatr Infect Dis J) Vol. 29 Issue 12 Pg. 1111-7 (Dec 2010) ISSN: 1532-0987 [Electronic] United States
• PMID: 20856164 (Publication Type: Journal Article, Multicenter Study, Randomized Controlled Trial, Research Support, Non-U.S. Gov't)

Chemical References

• Antibodies, Neutralizing
• Antibodies, Viral
• Japanese Encephalitis Vaccines
• Vaccines, Attenuated

Topics

• Animals
• Antibodies, Neutralizing (blood)
• Antibodies, Viral (blood)
• Child, Preschool
• Cross-Over Studies
• Encephalitis, Japanese (immunology, prevention & control)
• Female
• Humans
• Immunization, Secondary (methods)
• Infant
• Japanese Encephalitis Vaccines (administration & dosage, adverse effects, immunology)
• Male
• Mice
• Thailand
• Vaccination (methods)
• Vaccines, Attenuated (administration & dosage, adverse effects, immunology)