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