title: Evaluation of Sofia fluorescent immunoassay analyzer for influenza A/B virus.
abstract: BACKGROUND
  The influenza virus causes seasonal epidemics which are associated with high morbidity and mortality. Rapid diagnostics tests (RDT) are frequently used to make a quick influenza diagnosis to confirm the clinical suspicion, despite their low sensitivity.
  
  
  OBJECTIVE
  Assess the performance of the Sofia Influenza A+B Fluorescence Immunoassay (Quidel, San Diego, CA).
  
  
  METHODS
  Nasopharyngeal swabs, taken from 241 patients (influenza A (n=73)/B (n=72), negative samples (n=96)) were analyzed using the Sofia Influenza A+B Fluorescence Immunoassay, BinaxNOW Influenza A/B antigen kit (Alere Inc., USA), Directigen EZ Flu A and B (Becton Dickinson, USA), real-time RT-PCR and an influenza virus culture.
  
  
  RESULTS
  There was a significant difference between the performance of rapid antigen tests and the Sofia FIA, when compared to the RT-PCR, in the detection of influenza strain A and B. Indeed, the Sofia FIA displayed sensitivities of 82.2% and 77.8% for strains A and B respectively, whereas sensitivities of BinaxNOW Influenza A/B antigen kit, and Directigen Flu A and B were 54.8%, and 68.5% for influenza A, and 62.5%, and 52.8% for influenza B respectively. The average RT-PCR threshold cycle (C(t)) (±SD) for the Sofia Influenza A+B Fluorescence Immunoassay-positive specimens was higher than those of the BinaxNOW Influenza A/B antigen and the Directigen EZ Flu A and B kit positive specimens.
  
  
  CONCLUSIONS
  Compared to other RDTs, the Sofia Influenza A+B Fluorescence Immunoassay is a sensitive, and rapid method for the detection and discrimination between influenza A and B.
authors.affiliation: Department of Laboratory Medicine, Brain Korea 21 Graduate School of Medicine, College of Medicine, Korea University, Seoul, Republic of Korea. cklee@korea.ac.kr
authors.forename: Chang Kyu
authors.initials: CK
authors.lastname: Lee
authors.forename: Chi Hyun
authors.initials: CH
authors.lastname: Cho
authors.forename: Mi Kyung
authors.initials: MK
authors.lastname: Woo
authors.forename: Agnes E
authors.initials: AE
authors.lastname: Nyeck
authors.forename: Chae Seung
authors.initials: CS
authors.lastname: Lim
authors.forename: Woo Joo
authors.initials: WJ
authors.lastname: Kim
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D019411:Clinical Laboratory Techniques / Q000379:methods*; D005260:Female; D019085:Fluorescent Antibody Technique, Direct / Q000379:methods; D006801:Humans; D007223:Infant; D009980:Influenza A virus / Q000276:immunology / Q000302:isolation & purification*; D009981:Influenza B virus / Q000276:immunology / Q000302:isolation & purification*; D007251:Influenza, Human / Q000175:diagnosis* / Q000821:virology*; D008297:Male; D008875:Middle Aged; D009305:Nasopharynx / Q000821:virology; D012680:Sensitivity and Specificity; D013997:Time Factors; D055815:Young Adult