How is a PPD skin test considered normal?

Patient's question:

No

Doctor's answer:

After the skin test, the reaction should be checked within 48 to 72 hours. A redness alone should not be used as the sole criterion. If there are pinpoint red spots or slight redness and swelling at the injection site, and the hardened nodule has a diameter of less than 0.5 cm, it is considered a negative reaction.