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. BCG vaccination usually has some reactions at the vaccination site, and some parents who do not understand the precautions for BCG vaccination can easily make mistakes and lead to adverse consequences. Generally speaking, the skin at the site of vaccination is slightly red and swollen for 2-3 days after vaccination, but this will soon subside. In about 4 weeks, the area will gradually become red again and small white pustules (also called grouting) will appear, and then they will break down on their own, with some pus, and then gradually scab will form, leaving a slight scar after the scab falls off, which is normal for about 2-3 months. Remember, don’t pick it up by yourself, so as not to cause infection and unpredictable consequences. In a few cases, due to the different conditions of the body, the ruptured area has not been scarred or the left axillary lymph nodes are swollen, so you can go to the original vaccination unit for examination and treatment, but do not handle it by yourself. Precautions after BCG vaccination: 1. During the period of septicemia, use a clean handkerchief to wrap the area when bathing to avoid getting wet; 2. Keep the area clean, do not scratch with your hands, cut your nails and change your underwear regularly; 3. The vaccination will not cause systemic reactions, but if you have fever and other conditions, you should go to the hospital promptly; 4. Other preventive injections should be given in another arm (it is recommended to go to a regular hospital or preventive clinic); 5. Tuberculin test, also known as PPD test, if positive means that antibodies have been produced, if negative there is no antibody, still need to be vaccinated again. Contraindicated groups for BCG vaccination: 1. newborns born prematurely, difficult to deliver, with obvious congenital malformations; 2. children with acute infectious diseases such as fever and diarrhea; 3. patients with chronic diseases such as heart, lung and kidney diseases, serious skin diseases, allergic skin diseases, neurological diseases and those with allergic reactions to vaccination.