PDD is a medical abbreviation.

The correct form of PDD is PPD, clinically referred to as tuberculin test.

tuberculin test refers to the injection of tuberculin into the skin of the body, and according to the skin reaction of the injection site to determine tuberculosis vaccination or tuberculosis infection test. If there is no redness and induration at the pinhole of the subject, it is negative, indicating that the subject has not been vaccinated, the vaccination has not been successful or is not infected with Mycobacterium tuberculosis. If the subject is between 3 months and 3 years old, BCG vaccination can be re-inoculated. If the redness and induration at the pinhole is greater than 5mm, it is positive, indicating that the subject has a history of vaccination, tuberculosis infection or is infected with tuberculosis. At this time, the subject should go to the hospital for sputum culture, CT, MRI and other examinations in time to confirm whether the infection or infection is present.