Performance evaluation of Elecsys SARS‐CoV‐2 Antigen immunoassay for diagnostic of COVID‐19
María Caridad Montalvo Villalba, Elena Sosa Glaria, Licel de los Ángeles Rodríguez Lay, Odalys Valdés Ramírez, Dayana Vallina García, Amely Arencibia García, Javier Martínez Alfonso, Dunia M. Menes Llerena, Loida Torres Pérez, Sonia Resik, María Guadalupe Guzmán Tirado
Abstract
One of the challenges for control and prevention of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is the early diagnostic at the point of care. Several tests based on qualitative antigen detection have been developed; one of these is Elecsys SARS-CoV-2 Antigen immunoassay (Roche Diagnostics). In total, 523 nasopharyngeal swabs were randomly selected with the aims to evaluate sensitivity, specificity, cross-reactivity, positive and negative predictive value (PPV, NPV), and agreement of Elecsys SARS-CoV-2 Antigen immunoassay using reverse transcription-polymerase chain reaction (RT-PCR) STAT-NAT® coronavirus disease-2019 as reference test. Cross-reactivity was estimated using samples positive by RT-PCR to other respiratory viruses (influenza virus, parainfluenza virus, rhinovirus, coronavirus OC43, and HKU1). The overall sensitivity of Elecsys SARS-CoV-2 Antigen was 89.72% (288/321); specificity was 90.59% (183/202); and cross-reactivity to other respiratory viruses were not detected. Elecsys SARS-CoV-2 Antigen immunoassay showed a high sensitivity in samples with cycle threshold value <30, which ranged from 92.81% to 95.40%, independently of symptoms. PPV and NPV were 93.81% and 84.72%, respectively. The κ coefficient was 0.79 (95% confidence interval: 0.73-0.84), showing substantial agreement between both tests. The results suggest Elecsys SARS-CoV-2 Antigen immunoassay could be used as an alternative to RT-PCR testing, or in complement with it, to identify infectious individuals and reduce SARS-CoV-2 transmission.