If the local redness and swelling at the inoculation site, it is generally a reaction to vaccination, mild cases do not need to be dealt with, and severe cases can be localized hot compresses. If the whole arm is red and swollen, may be parents did not pay attention to the inoculation place cleanliness and hygiene, the inoculation place occurred bacterial infection, may also be an allergic reaction caused by angioneurotic edema. In this case, you should go to the hospital. Especially if it is accompanied by fever at the same time, check the blood routine for increased white blood cells and increased c-reactive protein, usually considered as bacterial infection, requiring local disinfection, oral or intravenous antibiotics. If it is just an allergic reaction, oral loratadine tablets or cetirizine drops should be taken to fight allergy.