强化计划免疫保护流动儿童健康朱寅生，于莲芳找单位最大的特点是：施工队伍无固定驻地、常年流动；分散在全国３０多个工地上；家在农村的单身职工占９０％以上。每年职工家属千里迢迢来工地探亲者逾２０００人次，其中学龄前儿童常在１５００人次以上，探亲时间不固定，... Intensified immunization program to protect the health of migrant children Zhu Yinsheng and Yu Lianfang find the biggest feature of the unit is that the construction team has no fixed station and flows all the year round; it is scattered over more than 30 construction sites in the country; and more than 90% of single workers occupy rural areas. Every year, relatives and workers of thousands of families come to the site to visit relatives and more than 2,000 people, of whom more than 1,500 are preschoolers or more, and their visiting time is not fixed.