Rapid Selection of Oseltamivir- and Peramivir-Resistant Pandemic H1N1 Virus during Therapy in 2 Immunocompromised Hosts

Pandemic 2009 H1N1 virus isolates containing the neuraminidase inhibitor resistance mutation H275Y have been reported. We describe rapid selection for the H275Y resistance mutation during therapy in 2 immunocompromised individuals at 9 and 14 days of therapy, as well as the first described case of clinically significant resistance to peramivir.