当病原体侵入人体时,身体就产生一种抵抗这种病原体的物质,叫作抗体。如再发生这种病原体侵入人体,人体就有抵抗力而不会得此病。预防接种就是根据这个原理进行人工预防。婴儿出生以后,随着一天天长大,原体内由母体带来的抗体(即抵抗疾病的能力)逐渐减弱或消失,因此,必须适时地给儿童进行预防接种,以增强儿童防病能力,减少其患传染病的几率,维护儿童健康成长。 When pathogens invade the body, the body produces a substance that is resistant to the pathogen, called an antibody. Such as the recurrence of this pathogen invades the body, the body will have resistance and will not get the disease. Vaccination is based on the principle of artificial prevention. After the baby is born, as one grows up day by day, the antibody (that is, the ability to resist disease) brought by the mother gradually diminishes or disappears in the original body. Therefore, the child must be vaccinated in a timely manner so as to enhance the child’s disease prevention ability and reduce its The risk of infectious diseases, to maintain healthy growth of children.