BCG vaccination is given to newborn infants and children to prevent the occurrence of childhood tuberculosis, especially those with severe types of tuberculosis, such as tuberculous meningitis. BCG vaccination is good for the healthy growth of children. The main reactions to BCG vaccination: 1. Within 2-3 days after intradermal BCG vaccination, there will be slight redness and swelling on the skin of the vaccination site, which is a non-specific reaction and will disappear quickly. After about 2 weeks, there will be a local papule-like hard mass with redness and swelling, sometimes softening into a small white pustule, which will later break down on its own to form a superficial ulcer, usually not more than 0.5 cm, with a small amount of pus, and then gradually scab, leaving a slight scar after the scab falls off. It takes 2-3 months and is a normal reaction of BCG vaccine. 2.After BCG vaccination, a very small number of people may have abnormal reactions such as severe rash, purpura and shock, which should be treated promptly. Occasional reactions during vaccination: 1. Inflammation of lymph nodes About 1-2 months after vaccination, lymph nodes in the neck, underarm, and above and below the collarbone may become enlarged (greater than 1.0 cm). If the reaction is too strong, the swelling of lymph nodes is obvious, and pus ulcers or ruptures can be formed, or small pus scars can be found at the inoculation site. The reaction of intradermal injection is often stronger than that of the scratch method. In addition, those who have a positive test for old tuberculin (OT) may also have a strong reaction after inoculation. 2. Lupus-like reaction Related to the residual virulence of the strain of Mycobacterium tuberculosis. 3. Scarring The formation of scarring protrusions due to abundant granulation tissue, sometimes in the form of scars, is mostly seen in those who are inoculated by direct dermal scratching without an OT test. The above process usually lasts for about 2 months. This is a normal reaction, and the swollen lymph nodes near the vaccination site (mostly axillary lymph nodes) will subside on their own as the vaccination site heals. If an abscess is formed, you can ask the doctor to draw out the pus with a syringe to promote healing, which generally does not affect the child’s health. If there is pus outflow, sterile gauze or cotton can be used to gently wipe it away, do not squeeze it, and it will naturally heal and scab in about 2-3 months on average, and the scab should be shed naturally and not picked up early.