Sofia fia

The Sofia Quantitative Vitamin D FIA is a point-of-care (POC) immunofluorescence-based lateral flow assay (Quidel Inc., San Diego, USA). It is designed for in vitro quantitative determination of total 25(OH)D₃ using serum samples. Two steps are of immense importance, first serum preparation and secondly reagent application to the test strip. Quantitative testing ability ranges from 10 to 100 ng/ml. If the serum 25(OH)D₃ lies below or above aforementioned limits, test results will correspondingly be shown as: “ < 10 ng/ml” or “ > 100 ng/ml”. Complying with CDC recommendation in manufacturer validation, the index assay was correlated with the LC–MS/MS reference method (r = 0.91 [95% CI 0.87–0.94]) and thus met VDSP performance criteria [12 (link)]. The Quidel Sofia FIA is able to run a high number of point of care assays, which were previously tested. To the extent of our knowledge, there is currently no clinical practice study concerning the total 25(OH)D₃ POC.

Microbiological analysis for the etiological diagnosis of pneumonia included blood-culture (BD BACTEC™ blood culture systems), urine antigen test for Streptococcus pneumoniae and Legionella pneumophila detection (Sofia FIA^® Quidel Corporation, San Diego, CA, USA), and qRT-PCR targeting viral respiratory pathogens (Allplex™ Respiratory Panels 1, 2 and 3, Seegene, South Korea). For other less frequent bacterial pathogens causing pneumonia (Mycoplasma pneumoniae and Chlamydophila pneumoniae) a PCR of a pharyngeal swab was performed according to manufactures instructions (CerTest Biotec SL, Spain).
In patients with diagnosis of SARS-CoV-2 pneumonia, diagnosis of SARS-CoV-2 had been commonly done some days before admission using commercial RT-PCR (Allplex SARS-CoV-2 assay, Seegene, South Korea) on nasopharyngeal swabs. Alpha (lineage B.1.1.7) was the predominant SARS-CoV-2 variant present when samples of these patients were collected.

Clinics transitioned from the Quidel QuickVue® Influenza A+B to Sofia-FIA between October 2012 and April 2013. Both RIDTs are CLIA-waived rapid antigen tests [24 ]. This change was prompted by a CDC request that Wisconsin clinics serve as a testing site for automated transfer of daily results, as made possible by the wireless feature of Sofia-FIA [26 (link)]. The Sofia-FIA and QuickVue platforms have similar specificities, but Sofia-FIA demonstrates superior sensitivity due to immunofluorescence-based lateral-flow technology [27 (link)]. The Sofia package insert cites nasal swab sensitivity and specificity as 90% and 95% for influenza A and 89% and 96% for influenza B, respectively [24 ].
We used the In-vitro Diagnostic (IVD) CDC Human Influenza Virus RT-PCR Panel as our comparison standard [28 ]. This panel allowed for identification of influenza type and subtype. Cycle threshold values were reported for all specimens. All confirmatory testing was performed at the WSLH. In addition, a respiratory pathogen panel (RPP)—identifying 17 viral targets—was performed on all specimens [29 ].