Why does my child need a second TB skin test in 10 weeks?
The TB skin test can be falsely negative (e.g., show no reaction) in students who may have been infected recently (in the past several weeks). The TB germ grows slowly and your body’s immune system takes time to react to it. Therefore, when screening students who have been recently exposed to a person with active TB, you need to repeat the TB skin test 10 weeks later to be sure that you have not been infected with TB.
