Prospective evaluation of Coris Influ-A&B Respi-Strip and of BinaxNOW Influenza A&B assay against viral culture and real-time PCR assay for detection of 2009 pandemic influenza A/H1N1v in Belgian patients.

ABSTRACT

PURPOSE: Evaluation of the performance of two rapid (15') antigen detection tests (RAT), BinaxNOW Influenza A&B and Coris Influ-A&B Respi-Strip for the detection of A(H1N1)v2009. STUDY DESIGN: Between July 2009 and November 2009, 4105 respiratory specimens from patients with influenza-like illness attending seven public hospitals in Brussels were prospectively examined by two immunochromatographic RAT, followed by viral culture and/or specific real-time RT-PCR. RESULTS: Samples consisted predominantly of nasopharyngeal aspirates (NPA-41%), nasopharyngeal (NPS-37%) and throat swabs (TS-14%). The sensitivity and specificity of Coris RAT and BinaxNOW RAT were 36.6% and 99.7%, and 47% and 98.7% respectively compared to culture; and 33.7% and 99.6%; and 46.5% and 98.8% compared to RT-PCR. Significant differences in sensitivity could be observed when splitting up the samples by sample type and patient's age. NPA gave by far the highest sensitivities 51.1- 62% for Coris compared to culture and 62.6-78.4% for BinaxNOW. Sensitivities in paediatric NPS varied less between different hospitals (34-41.9%) being still much higher than in adult NPS (11.4-20%). TS resulted in unsatisfactory results: 13% sensitivity in children and 10.5% in adults. CONCLUSIONS: Both RAT showed excellent specificities, but insufficient sensitivities. Consequently, negative results should be confirmed. NPA are clearly superior to NPS orTS, and they stay the sample of choice for viral diagnosis.