BCG is a preventive vaccination used to prevent tuberculosis in children. The vaccination gives children a specific resistance to tuberculosis. Currently, most countries in the world have included BCG as one of the vaccines required for planned immunization. BCG vaccination is mainly given to newborn infants and children, and it can prevent the occurrence of childhood tuberculosis, especially those with severe types of tuberculosis, such as tuberculous meningitis. About 1-2 weeks after BCG vaccination, babies will have small red nodules with an average diameter of about 10mm, which will gradually grow and become slightly painful and itchy, but without fever; 6-8 weeks, they will form pustules or ulcers, which will gradually soften into white pustules and break down on their own with a diameter of 3-5mm; 10-12 weeks, they will start to scab, and after the scabs fall off, they will leave a small, slightly red scar, and later the red color will gradually turn into skin color. Usually no treatment is needed. However, attention should be paid to local cleanliness to prevent secondary infection. To avoid contact with water or scratching with hands, dry sterile gauze can be used to wrap the area. Many mothers are worried when they find abscesses at the vaccination site after giving their babies the BCG vaccination. In fact, abscessing of BCG vaccine is a normal reaction to vaccination. Generally, after BCG vaccination, if the immunity is strong, there will be symptoms of slight pus at the vaccination site, so pus at the BCG vaccination site is normal, as long as the pus is not very strong, there is no need to worry, as long as the local area is thoroughly cleaned and disinfected to avoid infection. If there is no pus, it means that the vaccination may not be successful and must be revaccinated, and if the vaccination is successful, there will be pus to form a card scar.