Fever after vaccination may be caused by the immune response caused by the vaccine itself, or it may be caused by a decrease in resistance after vaccination and the influence of the primary disease in the body. If there are other clinical symptoms accompanying the fever process, you should go to the hospital in time to identify the cause and deal with it symptomatically to avoid adverse consequences. Common causes 1. Influence of vaccine itself: the principle of vaccination is to inject bacteria or virus into the body after treatment, so that the body can produce immune response and gradually produce antibodies to prevent diseases, and since the injection is bacteria or virus, some vaccinated people may have feverish reaction, but the body temperature is generally below 38.5℃; 2. Influence of disease: some vaccinated people are themselves in disease state, such as cold, or in a potential disease state, the disease symptoms may be more obvious before and after vaccination, and the symptoms of fever may appear, in addition to an increase in body temperature, and may be accompanied by other clinical symptoms. For children with fever caused by the vaccine itself, they should rest in bed, drink more warm water, and use warm water baths and ice packs to lower the temperature; if the body temperature is higher than 38.5℃, they can apply drugs such as ibuprofen and acetaminophen for antipyretic treatment under the guidance of a doctor. If the fever is more than 24 hours old, accompanied by obvious symptoms such as cough, runny nose, nausea, diarrhea, vomiting, etc., it is considered to be secondary to a new infection, and the infection should be understood through blood tests and C-reactive protein, and antibiotics such as amoxicillin and cephalexin can be used under the guidance of the doctor for treatment. If it is due to viral infection, treatment should be carried out symptomatically. Note: After vaccination, pay more attention to rest and keep warm to prevent secondary infection; pay attention to keep the skin of the vaccination site dry and clean to avoid bacterial infection and aggravation of fever; if fever persists or there is other serious discomfort, seek medical examination and treatment in time.