• Antiviral;
  • influenza;
  • oseltamivir effectiveness;
  • resistance

Please cite this paper as: Dharan et al. (2011) Clinical and virologic outcomes in patients with oseltamivir-resistant seasonal influenza A (H1N1) infections: results from a clinical trial. Influenza and Other Respiratory Viruses 6(3), 153–158.

Nineteen patients with oseltamivir-resistant seasonal influenza A (H1N1) infections were randomized to receive oseltamivir or placebo. Nasopharyngeal swabs were obtained, and clinical and virologic outcomes were compared, stratified by early or late treatment. Neuraminidase inhibition assay and pyrosequencing for H275Y confirmed resistance. Twelve (63%) patients received oseltamivir; 8 (67%) received late treatment. Seven (37%) patients received placebo; 6 (86%) presented >48 hours after onset. Time to 50% decrease in symptom severity, complete symptom resolution, and first negative culture were shortest among the early treatment group. While sample size prohibits a strong conclusion, future studies should evaluate for similar trends.