Such a thing as false/positive TB quantiferon test

Posted by dmk21 @dmk21, Jul 3, 2023

In 2020, I tested positive for TB, shortly after having Covid. My quantiferon came back positive. I had a chest X-ray the following week, that was negative. Three months later another quantiferon, also negative and six months after that again negative. 2021, 2022 and 2023 all my quantiferon Blood tests have been negative. But my employee is requiring me to have yearly chest X-rays, which once again is negative.
My question is, will I ever not have to have an X-ray, if my quantiferon tests are negative?…..And a side note…I’ve been doing quantiferon bld tests for 20 years as I’m allergic to the skin test..thank you

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My understanding guantiferon is not BCG depedent (i also had BCG in childhood)
-Positive guantiferon is due to TB exposure
- the test has high specificity and high sensity, thats why considered gold standard.

You should weight all pros and cons on abx. 3 months is not too bad. Being exposed means tb can become active anytime later in life, especially when we are or will become immunocpmpromised.
I would talk to more than one md, yet all would rec to take meds.
I waited more than 10 years to take the meds after i had positove quantiferon test.


I worked in a hospital in 2018 when my rheumatologist did a quantiferon blood test and came back positive. Was treated for latent TB. After that test, every test for the next 5 years came back negative. Then in beginning of 2024 my rheumatologist did another (of many) and this came back positive. I truly do not trust the validity of this test. I went 5years 4 months (and there were lots of quantiferon test done in those years) to having a positive again. At doctors getting chest xray as I type this but can guarantee it will be negative.

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