Tuberculosis (TB) is a chronic respiratory infection, and people who come into close contact with infectious TB patients are often referred to as close contacts of TB patients. Because such people can become infected with TB bacteria through airborne droplets in close or frequent contact with patients, and may be infected with higher numbers of TB bacteria, they are more likely to develop the disease than others and should be given special attention. Studies have shown that an untreated patient with bacillary tuberculosis can infect 10-20 people around him/her with TB within 1 year. Family members who live with the patient, or people who live intensively in a space with the patient, such as civilian dormitories, student dormitories, prison dormitories, etc., colleagues who work in the same office as the patient and short-term contacts in the same confined space as the patient, such as by airplane or high speed rail, who are in close contact with the patient, may be close contacts of TB patients. Close contacts are at high risk of tuberculosis infection and morbidity and need to go to a designated tuberculosis hospital for timely examination.