Usually, people who have close contact with infectious tuberculosis are called close contacts of tuberculosis. These people are likely to be infected with a larger amount of tuberculosis bacteria due to close contact with the patient and are therefore more likely to develop the disease than other people and should be given special attention. Close contacts should always pay attention to whether they have symptoms of prolonged coughing and sputum production, and if they do, they should go to the hospital for relevant tests as soon as possible to avoid delaying diagnosis and treatment. Close contacts usually include several types of people: 1. family members who live with the patient, or people who live together in dense living spaces (such as civilian dormitories, student dormitories, prison dormitories, etc.); 2. colleagues who share offices with the patient; 3. people who have short-term contact with the patient in confined spaces, such as people who are in close proximity to the patient during long-haul airline flights.