Version July 2025
| Characteristic | TST | IGRA |
| Antigens used | Many: PPD | 3 (QFT) or 2 (T-SPOT) |
| Sample | Intradermal injection | Blood draw |
| Patient visits required | 2 | 1 |
| Distinguish between TBI and disease | No | No |
| Cross-reactivity with BCG | Yes | No |
| Cross-reactivity with NTM | Yes | Only rare species* |
| Differing threshold for positive values by level of risk for TBI | Yes | No |
| Causes boosting | Yes | No |
| Subject to boosting by previous TST | Yes | Unknown but possible |
| Durability over time (stays positive with or without treatment) | Yes | Unknown but likely |
| Difficulties with test reproducibility | Yes | Yes |
| Location of need for trained staff | "Bedside" | Laboratory |
| Age <2 years¶ | Recommended | Acceptable |
| Estimated specificity in BCG-unvaccinated children, % | 95 to 100 | 90 to 95 |
| Estimated specificity in BCG-vaccinated children, % | 49 to 65 | 89 to 100 |
| Estimated sensitivity (confirmed TB disease), % | 75 to 85 | 80 to 85 |
| Estimated sensitivity (clinical TB disease), % | 50 to 70 | 60 to 80 |
BCG: Bacille-Calmette Guérin; IGRA: interferon-gamma release assay; NTM: nontuberculous mycobacterium; PPD: purified protein derivative; TBI: tuberculosis infection; TST: tuberculin skin test; QFT: Quantiferon.
* Mycobacterium marinum, Mycobacterium kansasii, Mycobacterium szulgai, and Mycobacterium flavescens.
¶ Negative result of either the TST or an IGRA should be considered especially unreliable in a child younger than 3 months.