Fainting: Sudden fainting after injection. In mild cases, the person may only feel panic, nausea or numbness in the hands and feet, which may return to normal in a short time. In severe cases, the face is pale, the heart beats faster, cold sweat, and even sudden loss of intuition. The syncope is related to fasting, fatigue, poor room air, mental tension or fear, and is caused by momentary cerebral ischemia caused by the reflex peripheral vasodilation that occurs after stimulation. Aseptic pustule: formed by local tissue necrosis and liquefaction due to incomplete absorption of adsorbent (aluminum hydroxide or aluminum phosphate) or inaccurate inoculation site. Generally, around 24 to 48 hours after inoculation, a large redness or infiltration is seen at the injection site, and after 2 to 3 weeks, local hard nodules appear with pain, and swelling can last for weeks or months, followed by pus ulcers and rupture, which are not easy to heal. This situation should be treated in hospital. Allergic rash: taught commonly, the rash is varied, with urticaria being the most common, usually occurring hours to days after vaccination, and within 1 to 2 weeks after live vaccination, with anti-allergy medication being given in severe cases, with a good prognosis. Anaphylactic shock: Shock can occur in individual children after vaccination, and it occurs within minutes to half an hour after vaccination, manifesting as irritability, pallor, cyanosis, cold limbs and sweating, etc. In severe cases, confusion, blood pressure drops and incontinence. In such cases, the child should be sent to the pediatric department of the hospital immediately, or subcutaneous or intravenous epinephrine should be injected on the spot, and rescue should be organized in a hurry. Parents are also advised to observe their child at the scene for half an hour after vaccination before leaving. Angioneurotic edema: Within 1 to 2 days after individual children are vaccinated again, the scope of redness and swelling at the injection site increases and the skin shines, and in heavy cases the edema can expand to the whole upper arm and wrist. Treatment is local hot compresses and oral anti-allergy medication. Systemic infection after vaccination: Mostly, the child has immune deficiency, which causes systemic infection after vaccination. It should be treated with specific immunoglobulin injection or plasma transfusion.