The tuberculosis skin test is a tuberculin test. BCG vaccination is usually started in the neonatal period, but for those who were not vaccinated in the neonatal period, they can continue to be vaccinated in the adult period. The tuberculin test is divided into positive and negative results. A positive result indicates that BCG vaccination or infection with Mycobacterium tuberculosis has occurred, but it is not possible to distinguish between a positive result due to Mycobacterium tuberculosis infection and a positive result due to BCG vaccination. The other is negative. A negative result indicates that no BCG vaccination or no infection with Mycobacterium tuberculosis, but there is another group of people who are also negative, such as patients with severe malnutrition, HIV infection, measles, chickenpox, and cancer, etc. These people may also be negative for BCG vaccination.