RESUMEN
To describe the clinical and epidemiologic features of pandemic influenza A [H1N1] cases. This study was conducted in Saudi Aramco Medical Services Organization [SAMSO] facilities in the Eastern province of the Kingdom of Saudi Arabia [KSA]. Electronic medical records for H1N1 infected patients who visited SAMSO between June and October 2009 were reviewed retrospectively. Nasopharyngeal and oropharyngeal swabs were collected from suspected patients, and sent to the Ministry of Health [MOH] Regional Laboratory in Dammam, KSA to confirm the diagnosis. A total of 587 cases were diagnosed with H1N1 given an incidence rate of 3.5 per 1000. Most of the infected cases were outpatients. The study showed that H1N1 was more common in the younger age group [median age; 22 years], and in female dependents at all ages, which differs from that reported by other researchers. Influenza A H1N1 was more common in the younger age group and in female dependents, and it was more severe among pregnant women. In addition, obesity did not affect the frequency of H1N1 infection