Measuring T-Cell Response to SARS-CoV-2 Using Elecsys IGRA SARS-CoV-2 Assay

PurposeThis study aims to assess T-cell response in individuals with a previous severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection or coronavirus disease 2019 (COVID-19) vaccination using the Elecsys(R) IGRA SARS-CoV-2 assay that is designed to detect broad-spectrum T-cell response. Preliminary data show that SARS-CoV-2 can elicit a robust and durable T-cell response, which, in conjunction with antibody response, may contribute to infection control. Furthermore, studies have shown that T-cell response is not substantially affected by emerging variants. The Elecsys IGRA SARS-CoV-2 assay combines in vitro T-cell stimulation and an automated electrochemiluminescence immunoassay for interferon-{gamma} measurement to qualitatively detect T-cell-mediated response to SARS-CoV-2 in human whole blood. MethodsClinical sensitivity of the Elecsys IGRA SARS-CoV-2 assay in convalescent and vaccinated adults was evaluated in a prospective clinical study including two cohorts in Germany, while specificity was determined in participants who were unvaccinated, without prior knowledge of a SARS-CoV-2 infection, and non-reactive to the Elecsys Anti-SARS-CoV-2 and Elecsys Anti-SARS-CoV-2 S serology assays. ResultsThe Elecsys IGRA SARS-CoV-2 assay showed high sensitivity and specificity in detecting SARS-CoV-2-elicited T-cell response. The Elecsys IGRA SARS-CoV-2 assay was found to reliably detect T-cell response upon natural infections or vaccinations, with sensitivity exceeding 99%, which was maintained up to 307 days following the last dose of the vaccine and up to 736 days post-symptom onset. ConclusionMeasuring T-cell response in convalescent and vaccinated individuals is feasible and can be meaningful in providing a more complete picture of the immune status of individuals in conjunction with serology assays.