JAPANESE ENCEPHALITIS SURVEILLANCE IN CHINA (PROVINCE OF TAIWAN) DURING 1968-1971

II. AGE-SPECIFIC INCIDENCE IN CONNECTION WITH JAPANESE ENCEPHALITIS VACCINATION PROGRAM

抄録

A baseline age/morbidity pattern for Japanese encephalitis (JE) epidemic in China (Province of Taiwan) in the 1960s was sought in JE surveillance. The pattern is characterized by: (1) high incidence in age groups 2-4 years, (2) moderately high incidence in age groups 5-7 years, (3) negligible incidence in children under 1 year of age as well as in adults, and (4) the variability of relative height of peak incidence co-incident with the JE-epidemic size in situ.
Concurrently with surveillance, a JE-vaccination program was implemented by the Government. The children of target age groups received two doses of vaccine each year during April. Vigilant supervision was given to the campaign to achieve a high coverage rate with two-dose vaccination and meticulous record-keeping. During 1969-1972, 2-year olds were the exclusive target; 52.2% (1969), 71.5% (1970), 74.5% (1971) and 83.0% (1972) of the target age group were covered.
A considerable change from the baseline age/morbidity pattern seen in 1968 occurred during the above period. The comparison of epidemicity-adjusted incidence by year indicates that incidence reduction in the 2- and 3-year-old children in 1971 were substantial and suggests the possible impact of vaccination. The total JE incidence for the period 1968-1971 appears to be much lower in vaccinated population (23 reported and 8 confirmed/0.9 million) than in unvaccinated population (1, 330 reported and 679 confirmed/2.2 million) .