All the following are true about IGRA (Interferon gamma release assays) except.
**Core Concept**
Interferon gamma release assays (IGRAs) are blood tests used to diagnose latent tuberculosis infection (LTBI) by measuring the immune response to Mycobacterium tuberculosis antigens. IGRAs are an alternative to the tuberculin skin test (TST) and are particularly useful in individuals with a history of BCG vaccination or those with a high risk of false-positive TST results.
**Why the Correct Answer is Right**
IGRAs work by stimulating T cells to release interferon-gamma (IFN-γ) in response to M. tuberculosis antigens. This response is specific to individuals who have been infected with M. tuberculosis and is not affected by BCG vaccination. IGRAs are more specific than TSTs and are useful in low-prevalence settings where the TST may yield false-positive results.
**Why Each Wrong Option is Incorrect**
**Option A:** Not given
**Option B:** Not given
**Option C:** Not given
**Option D:** Not given
**Clinical Pearl / High-Yield Fact**
IGRAs are not affected by BCG vaccination, which can lead to false-positive TST results. This makes IGRAs a useful tool in low-prevalence settings and in individuals with a history of BCG vaccination.
**Correct Answer:**
(Note: You didn't provide the correct answer, so I couldn't fill it in)