Of the 1840 persons triaged, 379 (21%) were tested for influenza (i.e. 371 (20%) by rRT-PCR, 112 (6%) by rapid diagnostic test, and 89 (5%) by immunofluorescence). Of the 371 patients tested by rRT-PCR, 104 (28%) had pandemic (H1N1) and 42 (11%) had seasonal influenza A detected. There was a 0.51 correlation between rRT-PCR and rapid diagnostic test results among the 85 patients who were tested by both methods (p,0.001). In contrast, there was a 0.15 correlation between rRT-PCR and immunofluorescence results among the 57 who were tested by both methods. In comparison to patients with seasonal influenza, patients whose rRT-PCR tested positive for 2009 pandemic influenza A (H1N1) were younger (Figure 4 ). The median age of patients who tested positive for 2009 pandemic influenza A (H1N1) was 23 years versus 31 years for patients who tested positive for seasonal influenza A (p = 0.0007)( Table 1) . Patients whose rRT-PCR tested positive for 2009 pandemic influenza A (H1N1) were not more likely to be pregnant, report substance abuse, have other medical conditions (e.g. obesity), or require hospitalization within 2 days of developing symptoms than other patients (Table 2) . At ER presentation, 69 (66%) of the 104 patients whose rRT-PCR tested positive for 2009 pandemic influenza A (H1N1) reported a dry cough (mean duration = 3 days) versus 145 (55%) of 264 test negative patients (p = 0.03). Thirty-two (31%) the 104 patients whose rRT-PCR tested positive for 2009 pandemic influenza A (H1N1) had a productive cough compared to 53 (20%) of 262 test negative patients (p = 0.03). Patients whose rRT-PCR tested positive for 2009 pandemic influenza A (H1N1) presented with a median temperature of 38.5uC which, on average, started 2 days before admission [IQR1-3]. There were no differences in WBC at ER presentation between patients whose rRT-PCR tested positive for 2009 pandemic influenza A (H1N1) and patients who tested negative for 2009 pandemic influenza A (H1N1).