The day after vaccination, if there is no clear bacterial infection, unauthorized administration of cephalosporin is not recommended. If a patient happens to develop a bacterial infection after the vaccination, he or she may take cephalosporin as prescribed by the doctor after visiting the hospital and having a bacterial infection confirmed by blood tests such as routine blood tests and CRP (C-reactive protein). Although taking cephalosporin may increase the adverse effects of the vaccine, serious infections that are not controlled in time may have adverse consequences, so on balance, it is necessary to take cephalosporin even though it is risky to do so. However, cephalosporins should not be taken freely if there is no certainty of bacterial infection. On the one hand, because vaccine related adverse reactions are likely to occur after vaccination, taking cephalosporin and other drugs may increase the incidence of adverse reactions. On the other hand, cephalosporin is an antibacterial drug and should only be used when there is an indication for bacterial infection. Taking antibacterial drugs without certainty of bacterial infection may easily lead to bacterial resistance and will not have a therapeutic effect on the disease, but there is a possibility of side effects of the drug. Therefore, cephalosporin can be taken the day after vaccination, but it must be decided by the doctor after visiting the hospital and passing relevant tests.