Because BCG is a live vaccine, some reactions will occur after vaccination, and it is normal for the vaccination site to become septic and ulcerated. How long does it take for a newborn baby to ulcerate from BCG vaccination? Within 2-3 days after intradermal BCG vaccination in babies, there is slight redness and swelling on the skin at the vaccination site, which is a non-specific reaction and will disappear quickly. After about 2 weeks, there will be localized papule-like hard lumps with redness and swelling, sometimes softening into small white pustules, then breaking down on their own to form superficial ulcers, usually no more than 0.5 cm, with a small amount of pus, and then gradually scabbing, leaving a slight scar after the scabs fall off. It takes 2-3 months and is a normal reaction to BCG vaccination. The time of local reaction, symptoms, and the speed of healing of BCG vaccine varies with each baby’s body type. Some babies will have a reaction only 2 months after vaccination; some babies have a very mild reaction, with only a slight redness of the skin that heals quickly; some babies have obvious symptoms, with large red pustules that look scary. Vaccination for babies is the need to pay attention to the following points: 1, in the case of the child’s health vaccination, basically will require 30 minutes of observation at the vaccination site, if there is no abnormal reaction can be left. 2. Small redness, swelling and pressure pain may appear at the site of the injection, which will generally get better on its own after 24 hours. If there is a fever and other symptoms, it is not a big problem as long as it does not exceed 38.5°C. Do not give your baby a bath for 2 days as much as possible and keep the injection site dry and tidy. 3. If the abscess or ulcer at the inoculation site does not heal for more than 6 months, you should check again to see if the baby’s axillary lymph nodes are significantly enlarged, and it is recommended to take the baby to a tuberculosis clinic for examination. If the abscess is indeed a pustule, the pus should be extracted with a sterile syringe, and it can generally be cured in 2-3 times. 4. After BCG vaccination, the vaccination personnel will make a record on the newborn’s vaccination card. If there is no record on the vaccination card, you should promptly ask the hospital where the newborn was born for the reason, so that the vaccination can be carried out in time when it is available. Note: Redness, swelling and pustules are normal reactions to BCG vaccination and generally do not require special treatment. However, you must pay attention to keep the skin clean to prevent infection, wear loose clothing, and wait for the scabs to fall off on their own.