Antigen detection tests; also known as rapid infl uenza diagnostic tests (RIDTs) detect infl uenza viral antigens in clinical specimens. These rapid infl uenza diagnostic tests can provide results within 30 min or less. Hence the results are available in a clinically relevant time period. Diagnostic tests for detection of novel H1N1 infl uenza virus antigen may be of two main types: direct fl uorescent antibody (DFA) tests and rapid enzyme/optical immunoassays or assay for NA enzymatic activity. Direct fl uorescent antibody (DFA) staining of clinical specimens using specifi c monoclonal antibodies against novel H1N1 infl uenza virus antigen can be a reliable and relatively rapid technique for the pandemic novel H1N1 infl uenza virus detection. Studies of DFA detection of infl uenza viruses have shown highly variable results with sensitivities ranging from 40% to 100%. Recent analytical studies indicate that commercially available RIDTs can detect novel infl uenza A (H1N1) virus [17] . In a study Chan et al. showed that the rapid antigen tests they evaluated in their study have comparable sensitivity for detection of novel H1N1 infl uenza and seasonal infl uenza viruses [18] . Data on analytical sensitivity for detection of different viruses does not directly refl ect clinical sensitivity on patient specimens. However, only limited data have been published on the performance of RIDTs compared with RT-PCR for detecting the presence of novel infl uenza A (H1N1) virus in clinical specimens [19] . Compared to RT-PCR, the sensitivity of RIDTs for detecting novel infl uenza A (H1N1) virus infections ranged from 10% to 70%. The sensitivity of RIDTs to detect novel infl uenza A (H1N1) virus is equal to or lower than the sensitivity to detect seasonal infl uenza viruses [17] . Although these rapid tests do not differentiate between novel H1N1 2009 infl uenza virus and seasonal infl uenza A or even between subtypes H1 and H3 but they may provide useful information that might impact patient care. Understanding the limitations of rapid tests is very important to appropriately interpret results for clinical management of the disease [20] .