Close contacts of TB patients, i.e. in the same space as the open TB patient, including the same room, in a car, in a dormitory, in a classroom. It is usually more common for TB prevention and control in schools, as more students in schools gather together for classes and accommodation. If a student develops TB, the closely contacted teachers, students in the same dormitory, students in the same classroom, and even students in other classes playing soccer or attending classes together should be screened, including chest X-rays and other relevant examinations, to rule out the possibility of close contacts developing the disease.