Influenza Viruses Types in 2010-2011 Winter Season and Effectiveness of Oseltamivir Treatment

Objective: The aim of this multicentric prospective study was to evaluate the efficacy of a new bioequivalent formulation of oseltamivir for the treatment of influenza A, influenza B and H1N1 during the 2010-2011 influenza season.Materials and Methods: We compared the symptoms and signs of 300 pediatric patients presenting to three University hospitals with an influenza-like illness, between January and March 2011. Nasal swab specimens were collected from all children and tested by reverse-transcription polymerase chain reaction (RT-PCR) for influenza viruses. After randomization, half of the participants were prescribed oseltamivir, while the other half were observed conservatively. Forty patients who were followed-up for influenza prior to the study were also included into the evaluation.Results: Influenza was confirmed by RT-PCR in 129 children, 71 of whom were prescribed oseltamivir. The durations of symptoms such as fever, cough, nasal congestion and rhinorrhea were significantly shorter for patients who were treated with oseltamivir compared with untreated patients (for all symptoms p<0.002). Early initiation of oseltamivir therapy (within 48 hours of the onset of symptoms) was associated with more favorable outcomes and a earlier recovery than in patients for whom treatment was delayed (beyond 48 hours). Thirty-seven patients (28.6%) had H1N1, 44 (34.1%) had influenza A, 46 (35.6%) had influenza B, 1 (0.75%) had H1N1 plus influenza A and 1 (0.75%) had influenza A plus influenza B viruses. In the comparison of the duration of symptoms in different virus types, a statistically significant difference was only observed in patients with influenza B, who had a longer duration of cough (p<0.001), nasal congestion (p<0.001) and rhinorrhea (p<0.001). Conclusion: Oseltamivir is an effective treatment for the management of seasonal influenza and H1N1, and should be initiated immediately without waiting for laboratory confirmation of diagnosis.