The tuberculin test is an intradermal injection of tuberculin with a very small needle that does not cause significant pain and feels like insulin in a diabetic patient. The tuberculin test is a primary screening test to determine whether there is an existing tuberculosis. Although it is not a definitive diagnosis of tuberculosis, if the result is strongly positive, it indicates the possibility of tuberculosis infection and should be examined at a designated hospital. In the tuberculin test, if the erythema is <5mm, the result is negative, indicating that the person has not been infected with TB and has not been vaccinated. If the erythema is 5-20 mm, it is a positive result and may indicate that the patient has been infected with TB or has received BCG vaccine. If the erythema exceeds 2cm or if there are ulcers, blisters, or hard nodules, it is a strong positive result and requires further examination and treatment at the infection department of the designated hospital.