The novel influenza A/H1N1 virus has spread to most of the world's populations, and its spread has led to a pandemic alert situation [1–3]. As a result, at the end of 2009, the World Health Organization announced that the novel influenza A/H1N1 had reached pandemic status .
A variety of different diagnostic methods can be used to detect the presence of influenza viruses in respiratory specimens such as nasopharyngeal aspirates, including direct antigen detection tests, virus isolation in cell cultures, and detection of influenza-specific RNA by real-time reverse transcriptase (RT)-polymerase chain reaction (PCR) [5–10]. Albeit the gold standard for the diagnosis of influenza is virus isolation using chicken embryos or tissue culture method, it has the shortcomings such as time consuming and labor intensiveness; it takes between two to 14 days before results are available. Detection of virus-infected cells in nasopharyngeal secretions by direct or indirect immunofluorescent staining is widely used, but it is a difficult and technician-dependent technique still requiring two hours to complete .
For the effective control and treatment of novel influenza, rapid and cost-effective diagnosis is important. Rapid diagnosis of influenza allows the physician to begin antiviral treatment, thereby helping control nosocomial transmission of the infection [12, 13]. It also helps reducing costs and hospital stay. Rapid diagnostic tests (RDT), known as lateral flow rapid tests, have previously been shown to be cost-effective in pediatric patients [14, 15] and effective in controlling influenza epidemics in geriatric institutions [12, 16].
The NanoSign® Influenza A/B test is a rapid diagnostic test, which detects the viral nucleoprotein antigen of influenza virus. This kit has been popularly used in Korea and by Korean governmental organizations, including Korea Centers for disease control and prevention (CDC), since its high accuracy has been demonstrated, with a high sensitivity and specificity against seasonal influenza A viruses, including A/H3N2, A/H1N1 (seasonal) and H2N2 [17, 18].
This study evaluated the clinical accuracy and analytical sensitivity of the NanoSign® Influenza A/B kit in detecting novel influenza A/H1N1. Using two types of novel influenza A/H1N1, A/California/12/2009(H1N1) and clinically isolated wild type influenza A/H1N1, the sensitivity and detection limits of the NanoSign® Influenza A/B kit were evaluated in this study.