Analytical reactivity of 13 commercially available rapid influenza diagnostic tests with H3N2v and recently circulating influenza viruses

Influenza and Other Respiratory Viruses (Impact Factor: 2.2). 04/2014; 8(4). DOI: 10.1111/irv.12246


Rapid influenza diagnostic tests (RIDTs) used widely in clinical practice are simple to use and provide results within 15 minutes; however, reported performance is variable, which causes concern when novel or variant viruses emerge. This study's goal was to assess the analytical reactivity of 13 RIDTs with recently circulating seasonal and H3N2v influenza viruses, using three different viral measures.DesignVirus stocks were characterized by infectious dose (ID50) and nucleoprotein (NP) concentration, diluted at half-log dilutions, and tested with each RIDT and real-time RT-PCR.ResultsStrong correlation was observed between NP concentration and RIDT reactivity; however, only weak correlation was seen with ID50 or Ct values. Only four RIDTs detected viral NP at the lowest dilution for all influenza A viruses (IAV). Influenza A viruses not detected by more than one RIDT had lower NP levels. Of the 13 RIDTs, 9 had no significant differences in reactivity across IAV when compared to NP levels.Conclusions
Previous reports of RIDT performance typically compare reactivity based on ID50 titers, which in this study correlated only weakly with proportional amounts of viral NP in prepared virus samples. In the context of the strong correlation of RIDT reactivity with NP concentration, H3N2v was found to be as reactive as seasonal circulating IAV. While these findings may not reflect clinical performance of these RIDTs, measuring NP concentration can be useful in the future to assess comparable reactivity of available RIDTs, or to assess reactivity with newly evolving or emerging viruses.

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Available from: Roxanne Shively, Jan 16, 2015
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    ABSTRACT: Like other respiratory viruses, influenza is responsible for devastating nosocomial epidemics in nursing homes as well as in conventional wards and emergency departments. Patients, healthcare workers, and visitors may be the source of nosocomial influenza. Despite their limited sensitivity, rapid diagnostic tests for influenza can be of real value; they enable early introduction of measures to prevent spread and early specific antiviral treatment of cases. However, these tests cannot detect oseltamivir resistance, susceptibility testing being carried out only in specialist laboratories. Although resistance is rare, it can emerge during treatment, especially of very young children or immunocompromised patients. In the latter, the shedding of resistant influenza virus can last several weeks. Sporadic instances of nosocomial transmission among immunocompromised patients have been reported. The limitations of bedside tests for influenza make them unsuitable for use as stand-alone diagnostic tools. However, their limitations do not preclude their use for detection and subsequent management of nosocomial influenza, for which they are rapid, easy, and cost-effective. Recent developments in these tests look promising, offering prospects of increased sensitivity, increased specificity, and screening for antiviral susceptibility. Copyright © 2015 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.
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