TB skin test mainly refers to Mycobacterium tuberculosis test, also known as PPD test. Eating eggs does not affect the results of TB skin test, which is mainly used to determine patients with active TB infection. If the erythema under the skin is <5mm, it indicates a negative result, which means that there is no TB infection and no vaccination. If the erythema is 5-10mm it is weakly positive and if the erythema is 10-20mm it is positive. Both weakly positive and positive results indicate previous TB infection or vaccination. If the erythema is >2cm or there are blisters and hard nodules, it is a strong positive result, which indicates that the person may be actively infected with tuberculosis.