Many children may experience local skin redness, swelling, or even lumps after vaccination, which are caused by the local skin irritation caused by the drug solution, and can be treated with local iodophor disinfection. If the lump is large, you can use a hot towel for local hot compress, the effect is still quite good. These are not the major ones, but the most common adverse reaction is the vaccination reaction. Many children may have vaccination reactions on the day after vaccination or the next day, manifested as fever, rash, nausea, vomiting, poor mental status, diarrhea, etc. These symptoms usually last for 2-3 days, and symptomatic treatment can be given. The most common one is fever. If the child has repeated high fever and poor mental status, and the fever lasts for more than 3 days, it is necessary to go to the hospital for examination to exclude other causes. After all, after vaccination, the immune function of the body will be reduced for a short period of time and the probability of infection is relatively high.