Are false-positive TB tests common?

In 18 studies involving 1,169,105 subjects, the absolute prevalence of false-positive TST from NTM cross-reactivity ranged from 0.1% to 2.3% in different regions. Conclusions: The effect on TST of BCG received in infancy is minimal, especially > or =10 years after vaccination.

How long does BCG cause positive PPD?

A positive TST reaction as a result of BCG wanes after 5 years. Therefore, HCWs with previous BCG vaccination will frequently have a negative TST result (74,227–232).

Will Quantiferon gold be positive after BCG vaccine?

QFT is a simple, fresh blood test that produces more accurate results than the century-old skin test. Unlike the TST, QFT is not affected by Bacille Calmette-Guérin (BCG) vaccination.

Can BCG vaccine cause positive TB test?

People who were previously vaccinated with BCG may receive a TB skin test to test for TB infection. Vaccination with BCG may cause a false positive reaction to a TB skin test. A positive reaction to a TB skin test may be due to the BCG vaccine itself or due to infection with TB bacteria.

How can you prevent a false-positive TB test?

Health care providers are encouraged to use newer TB blood tests to screen for TB infection. In order to prevent false-positive reactions, TB blood tests are also the preferred method of TB testing for people 5 years of age and older who have received the BCG TB vaccine.

Does BCG vaccine cause false-positive TB test?

Why does the BCG vaccine cause a false-positive?

Background: Bacille Calmette-Guérin (BCG) vaccination is known to cause false-positive tuberculin skin test (TST) results from cross-reactions with mycobacterial antigens.

What can causes a false-positive QuantiFERON gold?

(1) False-positive results may occur in patients with prior infection with M marinum, M szulgai, or M kansasii. Negative: No IFN-gamma response to M tuberculosis antigens was detected. Infection with M tuberculosis is unlikely.

Can you get TB even if vaccinated?

This vaccine is not widely used in the United States, but it is often given to infants and small children in other countries where TB is common. The BCG vaccine is not very good at protecting adults against TB. You can still get TB infection or TB disease even if you were vaccinated with BCG.