Prospective surveillance of antiviral resistance in hospitalized infants less than 12 months of age with A(H3N2) influenza infection and treated with oseltamivir.

Background: Infants exhibit elevated influenza virus loads and prolonged viral shedding, which may increase the risk for resistance development, especially in cases of suboptimal exposure to antiviral therapy.

Methods: We performed a prospective surveillance of hospitalized infants undergoing oseltamivir therapy during the 2008-2009 and 2011-2012 influenza seasons at two paediatric hospitals in Germany. A total of 37 infants less than 1 year of age with laboratory confirmed influenza A(H3N2) infection received oseltamivir as per physician's order for 5 days (2008-2009 season: 2 mg/kg twice daily; 2011-2012 season: 2.