Performance of five FDA-approved rapid antigen tests in the detection of 2009 H1N1 influenza A virus

Authors


  • Disclaimer: The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or reflecting the views of the Department of the Air Force, Department of the Army, Department of Defense, or the US Government. This work was prepared as part of their official duties; and, as such, there is no copyright to be transferred.

Abstract

Rapid antigen tests are commonly used by clinicians for rapid, simple, point-of-care testing. Five rapid antigen tests were shown to have low sensitivity (40.3–58.8%) when compared to real-time RT-PCR using nasal wash specimens from patients with influenza-like-illness (N = 167) that were collected previously and confirmed as 2009 pandemic influenza A (H1N1)-positive by PCR. Rapid antigen test sensitivity correlated with virus levels in nasal secretions when comparisons were made to cycle threshold (CT) values obtained from real-time RT-PCR. When CT values are <25 (equating to viral concentrations of >104 TCID50/ml) sensitivity for all five rapid antigen kits was high (range: 83–94% positive); however, when CT values are >30 (102 TCID50/ml), sensitivities of only 16–18% were observed for four of five rapid antigen kits. The Directigen EZ Flu A + B test detected more positive samples (35%) at lower viral concentrations with CT values >30 when compared with other commercial kits (P = 0.05). Rapid antigen test results must be interpreted with caution, and negative specimens may need confirmation by sensitive molecular assays. J. Med. Virol. 84:1699–1702, 2012. © 2012 Wiley Periodicals, Inc.

Ancillary