It is normal for babies to develop pus after BCG vaccination. If the child does not have other uncomfortable symptoms such as fever, parents need not worry too much. Because BCG vaccine is an inactivated vaccine, about two weeks after vaccination, the vaccination site will become red and swollen, and about 10mm papular nodules will appear, and then the nodules will gradually soften into white pustules from the center, and the pustules will have the largest volume in about 6-8 weeks of vaccination, followed by absorption, breakage, scabbing, and finally the scabs will fall off, leaving about 5-6mm of scar. Parents are advised to disinfect the pustules 1-2 times a day with iodophor swabs and avoid getting water on the area to avoid infection, but if fever or other uncomfortable symptoms occur when pus is formed, the child needs to be taken to the hospital for symptomatic treatment as soon as possible.