Clinical features of the hospitalized patients with 2009 pandemic influenza A (H1N1) in Santa Fe, Argentina

Background During 2009 occurred the emergence and global spread of a novel influenza A (H1N1) virus. We describe the clinical and epidemiologic features of hospitalized patients who survived and patients who died because of pandemic 2009 influenza A (H1N1) infection reported in Santa Fe, Argentina, from May to July 2009. Methods Using medical charts, we collected data on 242 patients who were hospitalized with confirmed laboratory results (defined as positive by specific PCR for pandemic 2009 influenza A H1N1). Results During the study period, there were 242 cases of hospitalization or death. Of the 242, 46% were admitted to an intensive care unit (ICU) and 33·5% died. The mean age was 27·8 years for surviving and 39·6 for those who died. Twenty‐eight percent of hospitalizations involved persons under the age of 15 years; 33% of the patients were between the age of 15 and 44 years; and only 3·3% were 65 years of age or older. Sixty‐seven percent had an underlying medical conditions, including diabetes, obesity, heart and lung diseases, and pregnancy. Of the 242 patients, 68% had findings consistent with pneumonia. Treatment with oseltamivir was administered to 227 (93·8%) patients from which 38 received oseltamivir within 48 hours after the onset of symptoms. Conclusions The pandemic strain caused severe illness, including pneumonia and acute respiratory distress syndrome, and resulted in ICU admissions in 46% of patients and death in 33·5%. The mean age of hospitalized infected cases was lower than is common with seasonal influenza. Underlying medical conditions were common in the 67% the evaluated patients. Patients who died had a higher prevalence of comorbidities (86·4%) than those who survived (57%), suggesting that the presence of chronic illness may increase the likelihood of death. However, the severe illness was also identified among young, healthy persons.