It is normal for children to have a transient fever after vaccination. This kind of fever usually does not exceed 38℃, and the low fever can be easily receded, such as giving children more water or dispersing heat, and it will not be repeated after receding. Secondly, in addition to fever, the child often does not have other abnormalities, such as spirit and appetite, and the fever does not appear again the day after the vaccination. However, if the baby still has a persistent fever after the vaccination, and this temperature exceeds 38.5℃ or more, and is repeatedly accompanied by mental and appetite abnormalities at the same time, it is necessary to go to the hospital.