A positive TB skin test is not necessarily contagious. If the TB skin test is not strongly positive, the adult has been infected with TB and is resistant, in which case there is basically no possibility of infection. If the test is strongly positive, active tuberculosis may be present, but it is necessary to complete the relevant imaging tests and sputum culture to determine whether there is active tuberculosis. If the lung CT test is normal and sputum culture is negative for Mycobacterium tuberculosis, a positive TB skin test in this case is not infectious. If the test population is children, adolescents appear to be strongly positive, and at the same time after the lung CT test, the appearance of exudative lesions, the probability of active tuberculosis is relatively high, and has a contagious. If the skin test is positive for tuberculosis, it is recommended to consult a doctor in time, complete the relevant examinations and treat the symptoms according to the test results.