Background: The pandemic swine origin influenza A/H1N1 2009 virus (H1N1 2009) was rapidly spread out all over the world after it was first found in April, 2009. This study was made to compare the performance of nasopharyngeal swabs and nasopharyngeal aspirates for the SD Bioline rapid influenza antigen test.

Methods: From Aug to Nov, 2009 the SD Bioline rapid influenza antigen tests were conducted with the nasopharyngeal swabs and the nasopharyngeal aspirates from the 244 specimens of patients who had come to the hospital with influenza-like illness. The data from the examination were compared with the multiplex RT-PCR as a reference standard to obtain sensitivity, specificity, positive predictive value and negative predictive value.

Results: The sensitivity and the specificity of the SD Bioline rapid influenza antigen tests with the nasopharyngeal swabs were 75.8%, and 93.3% respectively, and the sensitivity and specificity with the nasopharyngeal aspirates were 61.3%, and 98.3% respectively.

Conclusion: Even if the nasopharyngeal aspirates showed the lower sensitivity than the nasopharyngeal swabs, since the specificity is higher, the nasopharyngeal aspirates are more useful because we can reduce false positive rate. (Korean J Clin Microbiol 2010;13:147-150)