Primary and booster immune responses to SA14-14-2 Japanese encephalitis vaccine in Korean infants

Attenuated SA14-14-2 Japanese encephalitis (JE) vaccine has been administer ed 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 th e first clinical evaluation of the vaccine outside of China, we monitored s ide effects in 84 children and evaluated antibody responses to a single dos e given as primary JE vaccination in 68 children, 1-3 years old (mean age 2 7 months). No significant adverse events were noted. Neutralizing antibodie s (geometric mean titer [GMT] of 188) were produced in 96% of the 68 subjec ts, In 10 other children who previously had been immunized with two or thre e 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 co mparison group of 25 children previously immunized with two doses of inacti vated vaccine, neutralizing antibody titers were detected in 16 (64%), Vira l specific IgM was detected in nine primary vaccinees (13%) but in others, IgM may have declined to undetectable levels in the four week postimmunizat ion sample. Live attenuated SA14-13-2 JE vaccine is a promising alternative to the only commercially available JE vaccine for national childhood immun ization programs in Asia. (C) 1999 Elsevier Science Ltd. All rights reserve d.