Vaccines are given to prevent certain specific diseases, which are not 100% preventable but not ineffective. Vaccines are processed viruses or bacteria that may cause serious illnesses and then injected into the body as antigens, allowing the body to develop an immune response that results in the production of antibodies. People who have been vaccinated with the appropriate vaccine will develop specific immunity to the actual pathogenic microorganisms they come into contact with, reducing the risk of spreading the disease and controlling the severity of the illness. In addition, specific vaccination can improve the immunity of infants and young children to a certain extent, as the immune system of infants and young children is still immature before the age of 5 years. Therefore, infants and children under 5 years of age have poor resistance, which can easily lead to bacterial and viral invasions and infections. Vaccination can increase the resistance to a particular disease, which in turn reduces the risk of contracting the disease and contributes to a healthier body for infants and young children. The significance of vaccination lies in the fact that after vaccination, the body will get rid of the corresponding infectious diseases or reduce the chances of infection, and vaccination is the most important preventive means to control infectious diseases at present.