Objectives: To assess the epidemiologic and clinical manifestations of the first wave of H1N1 influenza A patients. Methods: This study is a retrospective chart review of all patients admitted in King Saud Medical Complex, Riyadh, Kingdom of Saudi Arabia, from 22nd May to 31st August 2009, with a proven diagnosis of H1N1 influenza A. Only patients with a positive nasopharyngeal swab were included, and excluded when the swab was negative. Charts were then analyzed for epidemiological and clinical data. Results: A total of 153 patients with proven H1N1 infection were admitted, with a predominance of male patients (108 [71%]). Most patients were Saudis (111 [73%]), with 83 males (75%), and 28 females (25%). The mean age was 25 years (standard deviation; 9.45 years), and median age was 24 years. The most common symptoms in order of frequency were; fever (143 patients), cough (126 patients), sore throat (70 patients), headache (18 patients), shortness of breath (17 patients), myalgia (11 patients), diarrhea (9 patients), and vomiting (7 patients). Average duration of symptoms before admission was 3.55 days, and the average time of hospitalization was 4.8 days. Full recovery was obtained in 150 patients. Death occurred in 3 patients. Conclusion: True to its designation as a pandemic, H1N1 influenza A, has reached Saudi Arabia and poses a risk to the young population without immunity, and those with co-morbid disease, particularly of the lungs (bronchial asthma), and the pregnant. Despite its virulence in infecting people, deaths are far less than anticipated for such a novel virus. Social distancing can be recommended. However, further observation has to continue to substantiate these tentative preliminary findings.
