3 YEAR FOLLOW-UP-STUDY OF NATIONAL INFLUENZA VACCINATION PRACTICES INJAPAN

Study objective - To evaluate new national influenza vaccination pract ices which were started in 1987 under a revised law in Japan. Design - This was a three year, non-randomised cohort study with information c ollected by questionnaire between 1989 and 1991. Setting - Eight prima ry schools in the city of Yonago, Tottori, Japan. These schools were s elected from 23 schools in the city. Participants - Altogether 4251 pu pils (1355 boys and 2896 girls) in years 1-4 of the eight primary scho ols were included in this study, and followed up. Three years later, d ata for 1619 pupils (768 boys and 851 girls) were obtained and analyse d. Main results - The one-winter seasonal incidence rates of influenza -like disease were 13.4%, 29.9%, and 10.3% in 1989, 1990, and 1991 res pectively. The incidence rate of influenza-like disease in fully vacci nated pupils was significantly lower than that in unvaccinated pupils in 1990, but not in 1989 or 1991. Stepwise multiple regression analysi s showed that the incidence of influenza-like disease had a statistica l relationship with the frequency of vaccination and the school year ( R(2) was 0.0148). Standardised parameters of the frequency of vaccinat ion and the school year were -0.089 and -0.080 respectively. Conclusio ns - The preventive effects of influenza vaccine are not strong. There must be some unknown factors that affect the incidence of influenza. This vaccine is useful for pupils in the early school years who seem t o have less resistance. All pupils should not be inoculated with the v accine to reduce influenza in the community or school.