The health of children is the most important thing to parents. In order to increase the immunity of children and prevent infectious diseases, parents should go to the immunization station or hospital to give their children immunization shots in time. However, it should be noted that there are some cases that are not suitable for vaccination, otherwise it will not work as expected and serious reactions will occur. 1. Children with severe dermatitis, psoriasis, eczema and purulent skin diseases at the site of vaccination should be cured of these diseases before vaccination. Secondly, children who are having a fever (body temperature over 37.5℃) should find out the cause of the fever and get vaccinated after it is cured. The reason is that vaccination will cause a reaction of elevated body temperature and aggravate the disease; in addition, fever is often an early symptom of acute infectious diseases such as influenza, measles, meningitis, hepatitis, etc. Vaccination will not only accelerate the onset of the disease, but also aggravate it, making it complicated and making diagnosis difficult for doctors. At the same time, the antigenic components of the vaccine and the disease-causing bacteria can interfere with each other and affect the generation of immunity. In addition, children who are suffering from acute infectious diseases or recovering from them in less than 2 weeks should delay vaccination against the disease. 2. Children with serious heart disease, liver disease, kidney disease, or tuberculosis should not be vaccinated. This is because children with these diseases are often in poor health and cannot withstand the mild reactions caused by vaccination. Their diseased organs cannot add extra burden, so they tend to have heavier reactions after vaccination. In addition, the detoxification of the liver and excretion of the kidneys have to be strengthened after vaccination, which affects the recovery of diseased organs; 3. Children with severe malnutrition, severe rickets and congenital immunodeficiency should not be vaccinated. These children should not be vaccinated because they cannot produce immunity due to the lack of raw materials for the formation of immune factors or poor functioning of immune organs; 4. Children with allergies and asthma, urticaria, and allergies that have occurred before vaccination should not be vaccinated. Because the vaccine contains extremely small amounts of allergens, it will not have any effect on children in general, but for children with physical allergies, due to their extremely high sensitivity, allergic reactions can occur and bring harm to children. 5. Children with diarrhea and stools more than 4 times a day should not take live attenuated polio vaccine in sugar pills. This is because diarrhea can quickly excrete the sugar pill vaccine and lose its effect. In addition, diarrhea, if caused by a viral infection, can interfere with the vaccine to produce immunity. Children who have been in close contact with an infectious person during an epidemic of an infectious disease should not be vaccinated immediately, but must be vaccinated after the longest incubation period of the infectious disease has passed and they have not developed the disease. Children who are not suitable for vaccination but must be vaccinated, such as those who have been bitten by rabid dogs, should be vaccinated only under medical supervision and close observation.