Evaluation of Roche Elecsys® and Diasorin Liaison® Fully Automated SARS-CoV-2 Antigen Tests - Optimized Cutoffs Increase the Sensitivity Both in Children and in Adults

Roche Elecsys® and DiaSorin LIAISON® SARS-CoV-2 automated antigen tests (AATs) were evaluated both in children and adults. Elecsys® and LIAISON® AATs were less sensitive (78.5% and 69.0%, respectively) than the nucleic acid amplification test (NAAT), and the sensitivity was also lower in children (75.9% and 57.3%, respectively) compared to adults (82.5% and 72.0%, respectively), the specificity being 100%. However, the sensitivity of AATs could be increased substantially (overall 83.1% and 91.8%, respectively) in children and in adults, when the cutoffs were optimized. With adjusted cutoffs both tests attained the performance requirements set by the authorities for the antigen tests. Both AATs are machine readable and give a quantitative numeric result. Thus, the interpretation of these test results is more reliable compared to qualitative rapid antigen tests (RATs) especially at low value range, and the low reactive samples can be confirmed by NAAT to increase the specificity back to up ~100%.