Oseltamivir-Resistant Pandemic (H1N1) 2009 Virus Infections, United States, 2010–11

Aaron D. Storms, Larisa V. Gubareva, Su Su, John T. Wheeling, Margaret Okomo-Adhiambo, Chao-Yang Pan, Erik Reisdorf, Kirsten St. George, Robert Myers, Jason T. Wotton, Sara Robinson, Brandon Leader, Martha Thompson, Marjorie Shannon, Alexander Klimov, Alicia M. Fry

, and for the US Antiviral Resistance Surveillance Working Group

Author affiliations: Centers for Disease Control and Prevention, Atlanta, Georgia, USA (A.D. Storms, L.V. Gubareva, S. Su, J.T. Wheeling, M. Okomo-Adhiambo, A. Klimov, A.M. Fry); California Department of Public Health, Sacramento, California, USA (C.-Y. Pan); Wisconsin State Laboratory of Hygiene, Madison, Wisconsin, USA (E. Reisdorf); New York State Department of Health, Albany, New York, USA (K. St. George); Maryland Department of Health and Mental Hygiene, Baltimore, Maryland, USA (R. Myers); Minnesota Department of Health, Saint Paul, Minnesota, USA (J.T. Wotton); Maine Department of Health and Human Services, Augusta, Maine, USA (S. Robinson); Washington State Department of Health, Shoreline, Washington, USA (B. Leader); Texas Department of State Health Services, Austin, Texas, USA (M. Thompson); Delaware Health and Social Services, New Castle, Delaware, USA (M. Shannon)

Abstract

During October 2010–July 2011, 1.0% of pandemic (H1N1) 2009 viruses in the United States were oseltamivir resistant, compared with 0.5% during the 2009–10 influenza season. Of resistant viruses from 2010–11 and 2009–10, 26% and 89%, respectively, were from persons exposed to oseltamivir before specimen collection. Findings suggest limited community transmission of oseltamivir-resistant virus.

During the 2009–2010 influenza pandemic, when pandemic (H1N1) 2009 virus was the predominant circulating influenza virus (1), the prevalence of oseltamivir-resistant pandemic (H1N1) 2009 viruses in the United States was 0.5%. Of the patients with oseltamivir-resistant virus infection, 89% had been exposed to oseltamivir before specimen collection (2). We describe patients with oseltamivir-resistant pandemic (H1N1) 2009 virus infections during the 2010–11 influenza season.