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Primary and booster immune responses to SA14-14-2 Japanese encephalitis vaccine in Korean infants
1Department of Pediatrics, Yonsei University College of Medicine, Seoul, Korea.
Insights
The live attenuated SA14-14-2 Japanese encephalitis (JE) vaccine is safe and effective for children. This study shows promising antibody responses in primary and booster vaccinations outside China.
Area of Science:
- Immunology
- Vaccinology
- Pediatrics
Background:
- The SA14-14-2 Japanese encephalitis (JE) vaccine has a proven safety and efficacy record in China.
- Recent interest in licensure outside China necessitates further clinical evaluation.
Purpose of the Study:
- To assess the safety and immunogenicity of the SA14-14-2 JE vaccine in children outside China.
- To evaluate antibody responses following primary and booster vaccination.
Main Methods:
- Clinical evaluation of side effects in 84 children.
- Antibody response assessment in 68 primary vaccinees (1-3 years old) and 10 children receiving a booster dose.
- Comparison of antibody titers in 25 children previously immunized with inactivated JE vaccine.
Main Results:
- No significant adverse events were observed.
- Primary vaccination induced neutralizing antibodies (GMT 188) in 96% of subjects.
- Booster vaccination in previously immunized children resulted in an anamnestic response (GMT 3378).
- Viral specific IgM was detected in 13% of primary vaccinees.
Conclusions:
- The live attenuated SA14-14-2 JE vaccine is a safe and immunogenic option for primary immunization.
- It demonstrates a robust anamnestic response when used as a booster.
- The vaccine represents a promising alternative for national childhood immunization programs in Asia.
Abstract:
Attenuated SA14-14-2 Japanese encephalitis (JE) vaccine has been administered safely and effectively to more than 100 million children in China since 1988 and recently, licensure of the vaccine in Korea has been sought. In the first clinical evaluation of the vaccine outside of China, we monitored side effects in 84 children and evaluated antibody responses to a single dose given as primary JE vaccination in 68 children, 1-3 years old (mean age 27 months). No significant adverse events were noted. Neutralizing antibodies (geometric mean titer [GMT] of 188) were produced in 96% of the 68 subjects. In 10 other children who previously had been immunized with two or three doses of inactivated JE vaccine, the booster administration of SA14-14-2 vaccine produced an anamnestic response in all, with a GMT of 3378. In a comparison group of 25 children previously immunized with two doses of inactivated vaccine, neutralizing antibody titers were detected in 16 (64%). Viral specific IgM was detected in nine primary vaccinees (13%) but in others, IgM may have declined to undetectable levels in the four week postimmunization sample. Live attenuated SA14-14-2 JE vaccine is a promising alternative to the only commercially available JE vaccine for national childhood immunization programs in Asia.