Close contacts of TB patients, i.e., in the same space with open TB patients, including in the same room, in the car, in the dormitory, and in the classroom. Usually more common school TB prevention and control, because more students in schools are gathered together in classes and housing, if a student develops TB, screening should be done for teachers in close contact around them, students in the same dormitory, students in the same classroom, and even students in other classes who play ball or attend classes together, including chest X-ray and other related tests to rule out the possibility of close contacts developing the disease.