A TB test, or tuberculosis test, should generally not be performed if an individual has had a positive result in the past. In addition, people who have recently been vaccinated with the BCG vaccine should wait 3-6 months before getting tested as it may yield unreliable results during this time period. If you are pregnant or have HIV/AIDS, testing is usually not necessary unless symptoms of TB appear. Lastly, if a person is receiving chemotherapy and/or immunosuppressants for any reason, they should avoid getting tested until their treatments are complete as their weakened immune system may cause false positive results.