The clinical course and outcome of all patients are summarized in Figure 1 . In the analysis of 15 patients who visited the emergency department, the mean interval between symptom onset and emergency room visit was 1.7 days ± 1.5 days (range, 0 to 5 days). In the analysis of all 18 patients, the mean interval between symptom onset and the start of oseltamivir phosphate (Tamiflu � , Roche, Basel, Switzerland) administration was 3.9 ± 1.6 days (range, 1 to 7 days). In addition, the mean interval between symptom onset and symptom improvement was 4.7 ± 1.7 days (range, 2 to 8 days).