It is particularly harmful if you take vaccination when you have a fever. The fever period resistance are relatively weak, if the vaccination, it is easy to lead to secondary infection, because the vaccination are inactivated viruses or bacteria, in normal immune conditions, often stimulate the body to produce antibodies, but in the case of weak immunity, it is easy to stimulate the body to cause the occurrence of disease, such as the hand, foot and mouth disease vaccine, it is likely to lead to the occurrence of hand, foot and mouth disease. If you take the B encephalitis vaccine, it may also lead to the occurrence of B encephalitis. Therefore, you should never take vaccination during fever. The resistance is weak and the immunity is not perfect when you have a fever, so if you take the vaccination, it may not stimulate the body to produce normal immunity and lose the effect of the vaccination, so it is absolutely not recommended to take the vaccination during the fever. In general, it is necessary to wait for more than two weeks for the fever to recover completely to recommend the vaccination, especially children are not allowed to play the vaccination.