Determinants of antiviral effectiveness in influenza virus a subtype H5N1

Abstract

Background. Oseltamivir is widely used as treatment for influenza virus A subtype H5N1 (hereafter, "H5N1") infection but, like any intervention, is not always effective. Methods. We used Avian Influenza Registry data from 10 countries to examine the risk of death in 215 patients with confirmed H5N1 infection who were treated with oseltamivir, according to viral clade, age, respiratory failure, and adjunctive treatment with corticosteroids or antibiotics. Results. The median age of infected individuals was 18 years, and 50 were male. The highest fatality rate occurred in a country with clade 2.1 virus circulation, and the lowest occurred in countries with clade 2.2 virus circulation (P