Clinical evaluation of Sofia Rapid Antigen Assay for detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among emergency department to hospital admissions

Abstract

Objective To determine the utility of the Sofia® SARS rapid antigen fluorescent immunoassay (FIA) to guide hospital bed placement of patients being admitted through the emergency department (ED). Design Cross-sectional analysis of a clinical quality improvement study. Setting Two community hospitals in Maryland. From 9/21/2020 to 12/3/2020, 2887 patients simultaneously received the Sofia® SARS rapid antigen FIA and SARS-CoV-2 RT-PCR assays on admission through the ED. Methods Rapid antigen results and symptom assessment guided initial patient placement while confirmatory RT-PCR was pending. The sensitivity, specificity, positive and negative predictive values of the rapid antigen assay were calculated relative to RT-PCR, overall and separately for symptomatic and asymptomatic patients. Assay sensitivity was compared to RT-PCR cycle threshold (Ct) values. Assay turnaround times were compared. Clinical characteristics of RT-PCR positive patients and potential exposures from false-negative antigen assays were evaluated. Results Overall agreement, sensitivity, and specificity for all patients was 97.9%, 76.6% (95% confidence interval (CI): 71%, 82%), and 99.7% (95% CI: 99%, 100%), respectively. No differences in performance were seen between asymptomatic and symptomatic individuals. As RT-PCR Ct increased, sensitivity of the antigen assay decreased. Mean turnaround time for the antigen assay and RT-PCR was 1.2 (95% CI: 1.0, 1.3) and 20.1 (95% CI: 18.9, 40.3) hours, respectively (p<0.001). No transmission from antigen-negative/RT-PCR-positive patients was identified. Conclusions While not a replacement for RT-PCR for detection of all SARS-CoV-2 infections, the Sofia® SARS antigen FIA has clinical utility for potential initial timely patient placement.

Clinical Accuracy of Instrument-Read SARS-CoV-2 Antigen Rapid Diagnostic Tests (Ag-IRRDTs)

“…Thus, the likelihood of false-negative antigen test results becomes higher at lower viral loads. While some studies detected no difference in the mean Ct values between symptomatic patients and asymptomatic patients [ 41 ], others reported that symptomatic patients displayed lower Ct values than asymptomatic COVID-19 patients, and a Ct value of 30 is the threshold for SARS-CoV-2 infectivity [ 22 , 38 ]. Moreover, it was shown [ 37 ] that different sensitivity versus Ct value patterns prevail in symptomatic and asymptomatic patient groups.…”

Supporting Technologies for COVID-19 Prevention: Systemized Review

“… (a) Cepheid’s Xpert Xpress SARS-CoV-2 test [ 39 ], (b) the work procedure of LabCorp COVID-19 test home collection kit [ 41 ], (c) Abbott’s ID NOW COVID-19 rapid test procedure [ 40 ], (d) Accula SARS-CoV-2 test [ 42 ], (e) Cue COVID-19 [ 43 ], (f) Sofia SARS Antigen FIA [ 44 ], (g) BD Veritor System for Rapid Detection of SARS-CoV-2 [ 45 ], and (h) Abbott BinaxNOW Antigen Self-Test [ 46 ]. FIA: fluorescent immunoassay.…”

Utilization of rapid antigen assays for detection of severe acute respiratory coronavirus virus 2 (SARS-CoV-2) in a low-incidence setting in emergency department triage: Does risk-stratification still matter?

“…To the Editor-We read with interest the article by Smith et al 1 describing the use of rapid antigen detection (RAD) for severe acute respiratory coronavirus virus 2 (SARS-CoV-2) in guiding hospital admission triage. Given the rapid turnaround of pointof-care testing, various studies have utilized RAD tests at the point of entry into the healthcare system.…”

“…Given the rapid turnaround of pointof-care testing, various studies have utilized RAD tests at the point of entry into the healthcare system. [1][2][3][4] However, most of these studies have occurred during periods of heightened transmission, with detection rates of 5%-21%. [1][2][3][4] RAD testing in clinical scenarios with lower incidence, such as asymptomatic individuals, may potentially result in low detection rates with high false-positive rates.…”

“…[1][2][3][4] However, most of these studies have occurred during periods of heightened transmission, with detection rates of 5%-21%. [1][2][3][4] RAD testing in clinical scenarios with lower incidence, such as asymptomatic individuals, may potentially result in low detection rates with high false-positive rates. 5 False-positive RAD tests have resulted in SARS-CoV-2negative patients being admitted to coronavirus disease 2019 (COVID-19) cohort wards, with subsequent nosocomial transmission.…”