Oseltamivir-Resistant Pandemic (H1N1) 2009 Virus, South Korea

To identify oseltamivir resistance, we analyzed neuraminidase H275Y mutations in samples from 10 patients infected with pandemic (H1N1) 2009 virus in South Korea who had influenza that was refractory to antiviral treatment with this drug. A neuraminidase I117M mutation that might influence oseltamivir susceptibility was detected in sequential specimens from 1 patient