Evaluation of the Sofia Influenza A + B fluorescent immunoassay for the rapid diagnosis of influenza A and B

Abstract

Rapid influenza diagnostic tests (RIDTs) can facilitate the appropriate prescription of antivirals for influenza, obviate the need for unnecessary testing and antibacterial agents and allow the implementation of infection control measures. However, the reported sensitivities and specificities of different RIDTs vary widely in clinical settings, as does assay ability to distinguish between influenza types and subtypes. To evaluate the performance of the Sofia Influenza A + B fluorescent immunoassay (FIA) for the detection of influenza A and B during the 2013 Southern Hemisphere influenza season, a total of 209 consecutive respiratory tract swabs from adult patients with an influenza-like illness were tested by both Sofia Influenza A + B and an in-house real-time, reverse transcription-polymerase chain reaction (RT-PCR) assay. Compared to RT-PCR, the sensitivity and specificity of the Sofia Influenza A + B FIA for detection of influenza A was 72.4% and 98.3%, respectively. Too few influenza B positive samples were available during the study to accurately assess the Sofia's performance for influenza B detection. The sensitivity of Sofia Influenza A + B FIA for both influenza A and B detection correlated with the amount of influenza RNA present in the sample as indicated indirectly by the RT-PCR cycle threshold (Ct ). In conclusion, the Sofia Influenza A + B FIA continues to perform well as a RIDT with the circulating influenza strains of the 2013 Southern Hemisphere influenza season.

Evaluation of a rapid antigen detection point-of-care test for respiratory syncytial virus and influenza in a pediatric hospitalized population in the Netherlands

“…Our results show that performance of Sofia FIA, above all for sensitivity, is poorer than expected from other studies (Hazelton et al, 2014). Furthermore, rate of false positives is high, in particular for Influenza B.…”

Performance of the Quidel Sofia rapid influenza diagnostic test during the 2012–2013 and 2013–2014 influenza seasons

“…Influenza infections are an important cause of morbidity and mortality worldwide in pediatric and adult patients . Early identification of influenza virus as the cause of a respiratory illness is essential for managing patients, facilitating appropriate use of antiviral medications, avoiding unnecessary antibiotic prescriptions, and implementing infection control measures …”

“…[1][2][3] Early identification of influenza virus as the cause of a respiratory illness is essential for managing patients, facilitating appropriate use of antiviral medications, avoiding unnecessary antibiotic prescriptions, and implementing infection control measures. 1,2,4,5 Rapid influenza diagnostic tests (RIDTs) are point-of-care tests that detect influenza viral antigens with quick results, usually 30 minutes or less. The Sofia Influenza A+B Fluorescent Immunoassay (Quidel Corporation, San Diego, CA) uses immunofluorescence-based lateral-flow technology to identify viral nucleoprotein antigens in nasal swabs, nasopharyngeal (NP) swabs, and NP aspirates/washes.…”

Evaluation of a two-stage testing algorithm for the diagnosis of respiratory viral infections

“…Because patients testing positive by Sofia® did not undergo further testing, we could not determine the true sensitivity and specificity of this test compared to FilmArray®. Previous studies have shown Sofia® specificity to be high, with a recent meta-analysis reporting a pooled specificity of 95.3% but sensitivity of only 75.3% for influenza A & B, and pooled specificity of 97.8% and sensitivity of 80% for RSV (Bruning et al, 2017;Gomez et al, 2015;Hazelton et al, 2015;Noh et al, 2015). Similarly, we assumed that all patients testing negative by PCR were true negatives; it is possible that some of these patients could have had false negative tests, i.e.…”

“…The Sofia® Fluorescent Immunoassay is a rapid, relatively inexpensive lateral flow assay for influenza A and B. It is reported to have a high specificity (94-98.3%) but low sensitivity (72.4-74%) compared to molecular assays (Bruning et al, 2017;Gomez et al, 2015;Hazelton et al, 2015;Noh et al, 2015). It requires less than 5 minutes hands-on setup time and has a 10-15 minute run-time.…”