BCG vaccine is a preventive vaccine used to prevent tuberculosis in children, and after vaccination, it gives children a specific resistance to tuberculosis. Generally, after BCG vaccination, those who are strongly immunized will show symptoms of slight pus at the vaccination site, so pus in BCG vaccination is normal. If there is no pus, it means that the vaccination may not have been successful, and the vaccination must be repeated, and there will be pus if the vaccination is successful. The redness, swelling and pus usually start about 2 weeks after BCG vaccination. After 1-2 weeks, the vaccination site will become red and swollen, with an average diameter of about 10mm, and will grow gradually, with slight pain and itching, but no fever; 6-8 weeks, pustules or ulcers will form, gradually softening into white pustules that can break on their own, with a diameter of 3-5mm; 10-12 weeks, scabs will begin to form, leaving a small, slightly red scar after the scabs fall off, and later The red color gradually turns into skin color. BCG pus usually does not need to be treated and can heal itself after a period of time, but attention should be paid to local skin cleanliness to prevent secondary infection. The pus is usually healed and scabbed naturally after 2-3 months, and after the inoculation site is scabbed, the scab should fall off naturally and should not be picked off early. The baby’s health is generally not affected. Because each child’s constitution is different, the time of local reaction to BCG vaccination, the severity of symptoms, and the speed of healing are not quite the same. Some children have reactions only 2 months after vaccination; some children have mild reactions, with only slight skin elevation and redness, which quickly improve; some children have more severe symptoms, with more obvious local redness and swelling, larger pus pockets, and even swollen axillary lymph nodes, and longer recovery time. This is a normal reaction after BCG vaccination and there is no need to worry. However, if there is no reaction after 3 months of vaccination, it means that the vaccination has failed and it is necessary to go to the vaccination site for tuberculin test to decide whether to replenish BCG vaccination.