预防接种是控制传染病的最有效和效益最好的公共卫生措施,这一点通过由世界卫生组织发动的全世界免疫规划而消灭天花得到清楚地证实。在此成功的基础上,世界卫生组织又倡导了扩大的免疫规划,其目标是,使全世界儿童得到免疫,以预防已有疫苗的常见儿童疾病。不幸的是对许多传染病尚无疫苗可用或疫苗不够理想,因 Vaccination is the most effective and cost-effective public health measure to control infectious diseases, as evidenced by the elimination of smallpox by the World Health Organization’s worldwide immunization program. Building on this success, WHO has also advocated an expanded immunization program with the goal of immunization of children worldwide to prevent common childhood diseases of existing vaccines. Unfortunately for many infectious diseases no vaccine is available or the vaccine is less than ideal