Utility of the FebriDx point-of-care test for rapid triage and identification of possible coronavirus disease 2019 (COVID-19)

Objectives: The Coronavirus disease 2019 (COVID-19) pandemic is straining healthcare resources. Molecular testing turnaround time precludes having results at the point-of-care (POC) thereby exposing COVID-19/Non-COVID-19 patients while awaiting diagnosis. We evaluated the utility of a triage strategy including FebriDx, a 10-minute POC finger-stick blood test that differentiates viral from bacterial acute respiratory infection through detection of Myxovirus-resistance protein A (MxA) and C-reactive protein (CRP), to rapidly isolate viral cases requiring confirmatory testing.

Methods: This observational, prospective, single-center study enrolled patients presenting to/within an acute care hospital in England with suspected COVID-19 between March and April 2020. Immunocompetent patients ≥16 years requiring hospitalisation with pneumonia or acute respiratory distress syndrome or influenza-like illness (fever and ≥1 respiratory symptom within 7 days of enrolment, or inpatients with new respiratory symptoms, fever of unknown cause or pre-existing respiratory condition worsening). The primary endpoint was diagnostic performance of FebriDx to identify COVID-19 as a viral infection; secondary endpoint was SARS-CoV-2 molecular test diagnostic performance compared with the reference standard COVID-19 Case Definition (molecular or antibody detection of SARS-CoV-2).

Results: Valid results were available for 47 patients. By reference standard, 35 had viral infections (34/35 COVID-19; 1/35 non-COVID-19; overall FebriDx viral sensitivity 97.1% (95%CI 83.3-99.9)). Of the COVID-19 cases, 34/34 were FebriDx viral positive (sensitivity 100%; 95%CI 87.4-100); 29/34 had an initial SARS-CoV-2 positive molecular test (sensitivity 85.3%; 95%CI 68.2-94.5). FebriDx was viral negative when the diagnosis was not COVID-19 and SARS-Cov-2 molecular test was negative (negative predictive value (NPV) 100% (13/13; 95%CI 71.7-100)) exceeding initial SARS-CoV-2 molecular test NPV 72.2% (13/19; 95%CI 46.4-89.3). The diagnostic specificity of FebriDx and initial SARS-CoV-2 molecular test was 100% (13/13; 95%CI 70-100 and 13/13; 95%CI 85.4-100, respectively).

Conclusions: FebriDx could be deployed as part of a reliable triage strategy for identifying symptomatic cases as possible COVID-19 in the pandemic.