Performing both the TST and the IGRA maximizes the sensitivity of the results in children of any age with suspected tuberculosis, although it is mandatory in children under biological therapy (especially TNF-α antagonists) when the initial and repeat IGRA results are indeterminate or invalid, when the initial test results (TST or IGRA) are negative but there is a high clinical suspicion of TB, and when an initial TST result is positive in children previously vaccinated against BCG [22, 24]. Here, TNF is linked to tuberculosis.