Tuberculosis, or TB, testing is not often needed for those with low risk of becoming infected. The skin test screens for the illness; it provides no immunity. If part of a higher risk category, then test for TB annually, according to the National Center for Biotechnology Information.
The general public within the United States usually does not need to have the TB skin test because the average person's risk for contracting tuberculosis is low. However, schools sometimes require this test as part of a student's immunization record. The test is then required as often as the school district mandates.
People who use illegal drugs, people who spend significant time around at-risk populations, people who have compromised immune systems, and people who spend time around a person with the illness all have a higher risk of contracting tuberculosis and should be tested regularly. At-risk populations include prisons, nursing homes and homeless shelters. People who come from countries where tuberculosis is more common are also at an increased risk. In the case of such groups, testing is usually done on a yearly basis.
There is no harm in having multiple TB tests, but those who have had an allergic reaction to the test should not be tested in the future. The TB skin test is a low-risk way to screen for tuberculosis and is broadly tolerated, even by infants and pregnant women. The skin test uses no live bacteria, so it is not possible to become infected with tuberculosis through the test.