Many infants will have a low fever after vaccination. This is a normal reaction for children because vaccination itself is composed of bacteria, viruses and toxoid, and fever or systemic reactions will often occur in different degrees after vaccination. If the body temperature is below 38.5℃, there is no need to deal with it and it will be relieved by itself after 1-2 days of drinking more water. However, if the fever is particularly strong and the temperature exceeds 39℃, combined with nausea, vomiting and loss of appetite, it is recommended to take oral antipyretic drugs such as Merlin for treatment, and if necessary, it is necessary to go to the hospital for consultation.