Utility of FebriDx in early identification of possible COVID19 infection

Abstract

Background Reliable differentiation between uncomplicated and self-limiting acute respiratory tract infections (ARIs) and more severe bacterial respiratory tract infections remains challenging, due to the non-specific clinical manifestations in both systemic bacterial or viral infections. The current COVID-19 pandemic is putting extraordinary strain on healthcare resources. To date, molecular testing is available but has a long turnaround time and therefore cannot provide results at the point-of-care, leading to a delay in results thereby exposing patients to cross-infection and delay in diagnosis (1-3). Methods We prospectively evaluated the utility of FebriDx®, a point-of-care fingerstick blood test that can differentiate viral from bacterial ARIs through simultaneous detection of both Myxovirus-resistance protein A (MxA) and C-reactive protein (CRP), in rapidly determining viral cases requiring immediate isolation and confirmatory molecular testing, from non-infectious patients or bacterial infections that require antibacterial therapy.Results 75 consecutive patients were assessed and 48 eligible cases were tested with FebriDx®. Overall, 35 patients had FebriDx® test viral positive. All 35 patients had either positive rt-PCR (n=30) for COVID-19 or clinical picture highly suggestive of COVID-19 infection (PPV of 100% in a pandemic situation)[AB1] . In the 13 cases it was viral negative, rRT-PCR was also negative in all cases. In one case of LRTI, it was not possible to determine the exact cause of infection and a viral infection couldn’t be excluded. Including this patient, the NPV was 12/13 (92%) exceeding the NPV of rRt-PCR at 71% (12/17). Sensitivity was conservatively calculated at 97% (35/36) compared to 85.7% (30[RS2] /35) for rRt-PCR. Similarly the specificity of both FebriDx®and rRt-PCR was 100% (12/12).Conclusions In the current COVID-19, FebriDx® shows potential as a reliable POC test and a proxy marker of COVID-19 infection amongst inpatients in a secondary care setting. [AB1]35/35 equates to a sensitivity and specificity of 100% for COVID, would you be willing to say that instead of ‘near 100% ppv)? [RS2]I believe PCR was 85.7% (30/35), because PCR only detects the COVID cases

Horses for courses? Assessing the potential value of a surrogate, point‐of‐care test for SARS‐CoV‐2 epidemic control

“…The key risk in using any POCT is of a false-negative result leading to 90%, and specificities from 78% to 88%. [13][14][15][16] However, two recent studies from the UK evaluate FebriDx specifically for screening for SARS-CoV-2 in hospital: a small-scale pilot, 5 and a study nested within a non-randomised clinical trial of molecular POCTs. 6 These studies report impressive sensitivities and specificities of 100% and 93%, and 100% and 86%, respectively.…”

“…4 A number of evaluations are ongoing to consider the value of FebriDx in acute and primary care settings during the COVID-19 pandemic. 5,6 This short report explores the place of surrogate POCTs in the diagnostic mix in high-income settings, by considering the performance of FebriDx and SARS-CoV-2-specific POCTs on the market.…”

Horses for courses? Assessing the potential value of a surrogate, point-of-care test for SARS-CoV2 epidemic control

“…Reported sensitivities range from 64-90%, and specificities from 78-88% (13-16). However, two recent studies from the UK evaluate FebriDx specifically for screening for SARS-CoV2 in hospital: a small-scale pilot (5), and a study nested within a non-randomised clinical trial of molecular POCTs (6). These studies report impressive sensitivities and specificities of 100% and 93%, and 100% and 86% respectively.…”

“…FebriDx offers greatest value early in the clinical course, given the absence of reliable antigen POCTs and scarcity of molecular POCTs. However, reported sensitivity ranges for COVID and non-COVID patients in healthcare settings are wide (5,6,(13)(14)(15)(16). The test should therefore be positioned within a diagnostic algorithm, alongside other clinical and radiological markers, to optimise performance.…”

“…These include FebriDx, a low-cost POCT used to distinguish bacterial from viral infections and originally designed to support rational antibiotic prescribing (4). A number of evaluations are ongoing to consider the value of FebriDx in acute and primary care settings during the COVID-19 pandemic (5,6). This short report explores the place of surrogate POCTs in the diagnostic mix in high income settings, by considering the performance of FebriDx and SARS-CoV2-specific POCTs on the market.…”