Evaluation of Sofia fluorescent immunoassay analyzer for influenza A/B virus

Chang Kyu Lee, Chi Hyun Cho, Mi Kyung Woo, Agnes E. Nyeck, Chae Seung Lim, Woo Joo Kim

Research output: Contribution to journalArticlepeer-review

52 Citations (Scopus)


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. Objectives: Assess the performance of the Sofia Influenza A + B Fluorescence Immunoassay (Quidel, San Diego, CA). Study design: 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 (Ct) (±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. Conclusion: 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.

Original languageEnglish
Pages (from-to)239-243
Number of pages5
JournalJournal of Clinical Virology
Issue number3
Publication statusPublished - 2012 Nov

Bibliographical note

Funding Information:
This study was supported by a grant of the Korea Healthcare Technology R&D Project , Ministry of Health & Welfare, Republic of Korea (Grant No.: A103001 ).


  • Fluorescent immunoassay
  • Influenza
  • Rapid diagnostic test
  • Virus culture

ASJC Scopus subject areas

  • Virology
  • Infectious Diseases


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