It is better for babies not to have fever after vaccination, and if they have fever, it depends on the specific situation. If the fever is only low, there are no uncomfortable clinical symptoms and signs, and the baby has a good appetite, it is considered a normal reaction after vaccination, so there is no need to be nervous and just drink more water appropriately. However, if the baby’s fever after vaccination belongs to high fever, that is, the anal temperature is greater than 39℃ or more, or the baby is accompanied by other clinical symptoms, such as cough, nasal congestion, runny nose, vomiting, nausea, diarrhea, etc. It is usually considered that the temporary decrease of the body’s immunity after vaccination is caused by secondary viral or bacterial infection, and should be promptly diagnosed and treated at the hospital.