自１９８２年推行儿童计划免疫以来，尤其经过“四苗覆盖率”的三个８５％达标，预防的相应传染病发病规律发生了很大变化。本文根据我市１９６３～１９９６年疫情资料，试用圆形分布法，对麻疹、脊髓灰质炎（下称脊灰）、百日咳及白喉４种疾病推行计划免疫前后的发病季节... Since the introduction of the program of immunization for children in 1982, the incidence of corresponding communicable diseases has been greatly changed, especially after the three 85% of the “four seedling coverage rates” have been reached. Based on the epidemic data from 1963 to 1996 in our city, we tried the round distribution method to test the onset season of measles, poliomyelitis (polio), pertussis and diphtheria before and after planned immunization.