A rapid, high-sensitivity SARS-CoV-2 nucleocapsid immunoassay to aid diagnosis of acute COVID-19 at the point of care

Drain, P. K.; Ampajwala, M.; Chappel, C.; Gvozden, A. B.; Hoppers, M.; Wang, M.; Rosen, R.; Young, S.; Zissman, E.; Montano, M.

The LumiraDx SARS-CoV-2 antigen test was evaluated for diagnosing acute COVID-19 in adults and children across point-of-care settings. The investigational diagnostic test uses a high-sensitivity, microfluidic immunoassay to detect the nucleocapsid protein of SARS-CoV-2. Out of the 512 participants, aged 0-90 years, of this prospective validation study, 414 (81%)were symptomatic for COVID-19 and 123 (24%) swabs were positive for SARS-CoV-2 based on real-time PCR (rt-PCR) testing. Compared with rt-PCR, the 12-minute swab test had 97.6% sensitivity and 96.6% specificity within 12 days of symptom onset, representing the period of infectivity. All (100%) samples detected within 33 rt-PCR cycles were also identified using the antigen test. Results were consistent across age and gender. Despite being performed by minimally trained healthcare workers, the user error rate of the test system was 1%. The rapid high-sensitivity assay using nasopharyngeal or anterior nasal sampling may offer significant improvements for diagnosing acute SARS-CoV-2 infection in clinic- and community-based settings.