BinaxNOW® - An immunochromatographic test for the diagnosis of human influenza viruses: Comparison with viral culture and polymerase chain reaction

Purpose: A rapid test for influenza viruses (Binax NOW^® ) was evaluated.
Materials and Methods: In season-1, 35 respiratory samples were tested retrospectively; in season-2, 45 samples were tested prospectively [gold-standard: viral culture in season-1, culture+ reverse transcriptase-polymerase chain reaction (RT-PCR) in season-2].
Results: Sensitivity for Binax for influenza A was 59.3 and 0% in season-1 and -2, respectively. Sensitivity was low for influenza B (33.3% in season-1, 26.1% in season-2). Samples having low viral load were more likely to have a negative Binax test. Specificity of Binax was high (100 and 94.7% with influenza A and B, respectively).
Conclusion: Sensitivity information provided in the kit insert does not always reflect post licensure performance in clinical settings.