If the BCG vaccination is not successful, a new BCG vaccination is needed. BCG is currently the most effective and convenient way to prevent tuberculosis, and a tuberculin test is required to determine if the BCG vaccination is successful. The tuberculin test is usually performed three months after the BCG vaccination. A positive test means that the vaccination was successful, while a negative test generally means that the vaccination was not successful, although false negatives may occur. A negative test can be performed if there is cornified tuberculosis or if the immune system is extremely low, and if hormones and immunoglobulin are applied heavily, so an accurate judgment is needed at the hospital.