The Interferon Gamma Release Assay measures how strongly a patient’s immune system reacts to TB bacteria by testing a patient’s blood in a laboratory. Blood is collected in special tubes using a needle and delivered to a laboratory, which tests it.
Hanna looked at 350 patients at a Bronx medical clinic, surveying them about their ages, countries of birth and medical conditions. Hanna determined that the skin test is best for U.S.-born patients, unless they suffer from an immunosuppressive disease such as HIV/AIDS. For foreign-born patients, the blood test provides the most accurate results.

Profiles of Abramowitz, Jellinek and November can be found here.