[Article in Chinese]
          Hsu LC, Wu YC, Lin SR, King CC, Ho MS, Lu CF, Hsu HM, Chen KT, Horng CB
          National Institute of Preventive Medicine, Department of Health, Taiwan,
          R.O.C.
          J Microbiol Immunol Infect 1997 Aug;30(3):194-206

        In order to evaluate the Japanese encephalitis virus (JEV) vaccination
        program in rural Taiwan, we conducted a seroepidemiological survey of
        JEV among rural children 3 to 6 years of age in Taiwan. The children
        were selected through a systemic sampling following stratification by
        age of children in 4 selected aboriginal villages and 4 adjacent
        nonaboriginal villages. The overall vaccine coverage rate for the
        primary (2 doses) dose was 81.2% (1853/2281) with higher rates
        (87.7%-87.9%) found among the more recent birth cohort of 3 to 4 years
        of age. The neutralizing antibody (NT) against JEV was measured with
        plaque reduction neutralization test (PRNT) using Nakayama strain as the
        virus. With a positive NT antibody defined as > or = 1:10 dilution of
        serum yielding more than 50% plaque reduction, the overall JEV NT
        antibody positive rate among children receiving 3 doses of vaccine was
        67%. However, the age-specific positive rates varied significantly with
        varying ages; the lowest of 47% being among children 4 years of age
        which was lower than the rates of 68%, 76% and 87% among children of 3,
        5 and 6 years of age, respectively. This trend of rising seropositive
        rates of JEV antibody with increasing age among 4 and 6 years of age was
        also noted among children who had received no vaccine, suggesting the
        importance of natural infection among rural Taiwanese children. Despite
        the high frequency of natural infection, the seropositive rates of JEV
        antibody still correlated well with the dose of vaccine received, i.e.,
        67% (1122/1664), 66% (65/97), 33% (4/12) and 40% (19/47) for children
        receiving 3, 2, 1, and 0 dose of JE vaccines, respectively (P < 0.0001
        Chi-square for trend test). When stratified analysis by dose and by type
        of vaccines was conducted, a significantly higher seropositive rate of
        JEV NT antibody was noted among children receiving JE vaccine of Beijing
        type (87%) than children receiving Nakayama type (39%) (p < 0.0001,
        Chi-square test). Our data indicated that the JEV vaccination, in
        conjunction with JEV natural infection, has maintained high JEV NT
        antibody level among rural children of Taiwan.