众所周知,天花的消灭,小儿麻痹和麻疹等传染病的发病率大幅度下降,是国家采取了一系列综合措施实施成功的。这中间通过预防接种疫苗,控制疫情更是功不可没。预防接种疫苗是一种低投入高产出的健康投资,关系到千家万户身体健康,其社会效益之大无法估计。这里特别要指出的是,老年人也需要进行一些疫苗的接种。乙肝疫苗——非终身免疫,故经过隐性感染或接种过此疫苗 As we all know, the incidence of smallpox eradication, poliomyelitis and measles and other infectious diseases has dropped dramatically, and the country has adopted a series of comprehensive measures to implement the success. In the meantime, by controlling vaccination, it is even more important to control the epidemic. Vaccination is a low investment in high-yield health investment, relates to the health of millions of households, its social benefits can not be estimated. It is particularly pointed out here that the elderly also need some vaccination. Hepatitis B vaccine - non-lifelong immunization, so after a latent infection or vaccination of the vaccine