Fasting is not recommended for vaccination, because eating in moderation can replenish energy, improve the body’s tolerance and reduce adverse reactions after vaccination. However, for oral vaccines, such as polio vaccine and attenuated rotavirus vaccine, eating 30 minutes before and after vaccination should be avoided. Firstly, for people who are afraid of vaccination and have resistance to vaccination, anxiety and nervousness will occur with the injection, leading to vagal nerve disorder and causing excessive secretion of stomach acid, and if you fast at this time, you may experience nausea, pain and other symptoms of stomach discomfort. Secondly, for people who have previous diabetes or are old and weak, waiting for vaccination on an empty stomach may lead to discomfort symptoms such as panic, cold sweat and weakness because of objective factors such as long waiting time. In case of severe hypoglycemia, central nervous system symptoms such as dizziness, coma, incontinence, etc. may occur, which may be life-threatening in severe cases. For some patients with pre-existing heart disease, there may be insufficient blood supply to the heart when vaccination is given on an empty stomach, resulting in heartburn and other uncomfortable symptoms. It is recommended that before vaccination, you should learn about the precautions from the doctor specializing in vaccination, and avoid spicy and stimulating foods such as pepper, leek and ginger in addition to alcohol in your diet, and you can eat high protein foods such as eggs and milk in moderation to keep your body in a relatively good condition and reduce possible discomfort. After vaccination, pay attention to the cleanliness of the skin at the vaccination site to avoid local infection, and if uncomfortable symptoms appear, it is recommended to seek medical advice and scientific treatment in a timely manner.