Published at www.nejm.org October 8, 2009 (10.1056/NEJMoa0906695)
Hospitalized Patients with 2009 H1N1 Influenza in the United States, April–June 2009
Seema Jain, M.D., Laurie Kamimoto, M.D., M.P.H., Anna M. Bramley, M.P.H., Ann M. Schmitz, D.V.M., Stephen R. Benoit, M.D., M.P.H., Janice Louie, M.D., M.P.H., David E. Sugerman, M.D., M.P.H., Jean K. Druckenmiller, B.S., S.M.(N.R.M.), Kathleen A. Ritger, M.D., M.P.H., Rashmi Chugh, M.D., M.P.H., Supriya Jasuja, M.D., M.P.H., Meredith Deutscher, M.D., Sanny Chen, Ph.D., M.H.S., John D. Walker, M.D., Jeffrey S. Duchin, M.D., Susan Lett, M.D., M.P.H., Susan Soliva, M.P.H., Eden V. Wells, M.D., M.P.H., David Swerdlow, M.D., Timothy M. Uyeki, M.D., M.P.H., Anthony E. Fiore, M.D., M.P.H., Sonja J. Olsen, Ph.D., Alicia M. Fry, M.D., M.P.H., Carolyn B. Bridges, M.D., Lyn Finelli, Dr.P.H., for the 2009 Pandemic Influenza A (H1N1) Virus Hospitalizations Investigation Team
Background During the spring of 2009, a pandemic influenza A(H1N1) virus emerged and spread globally. We describe the clinicalcharacteristics of the patients who were hospitalized with 2009H1N1 influenza in the United States from April 2009 to mid-June2009.
Methods Using medical charts, we collected data on 272 patientswho were hospitalized for at least 24 hours for influenza-likeillness and who tested positive for the 2009 H1N1 virus withthe use of a real-time reverse-transcriptase–polymerase-chain-reactionassay.
Results Of the 272 patients we studied, 25% were admitted toan intensive care unit and 7% died. Forty-five percent of thepatients were children under the age of 18 years, and 5% were65 years of age or older. Seventy-three percent of the patientshad at least one underlying medical condition; these conditionsincluded asthma; diabetes; heart, lung, and neurologic diseases;and pregnancy. Of the 249 patients who underwent chest radiographyon admission, 100 (40%) had findings consistent with pneumonia.Of the 268 patients for whom data were available regarding theuse of antiviral drugs, such therapy was initiated in 200 patients(75%) at a median of 3 days after the onset of illness. Datasuggest that the use of antiviral drugs was beneficial in hospitalizedpatients, especially when such therapy was initiated early.
Conclusions During the evaluation period, 2009 H1N1 influenzacaused severe illness requiring hospitalization, including pneumoniaand death. Nearly three quarters of the patients had one ormore underlying medical conditions. Few severe illnesses werereported among persons 65 years of age or older. Patients seemedto benefit from antiviral therapy.
Source Information
The authors' affiliations are listed in the Appendix. This article (10.1056/NEJMoa0906695) was published on October 8, 2009, at NEJM.org.
Address reprint requests to Dr. Jain at the Centers for Disease Control and Prevention, 1600 Clifton Rd. NE, MS A-32, Atlanta, GA 30333, or at bwc8{at}cdc.gov.
Kotsimbos, T., Waterer, G., Jenkins, C., Kelly, P. M., Cheng, A., Hancox, R. J., Holmes, M., Wood-Baker, R., Bowler, S., Irving, L., Thompson, P., on behalf of the Thoracic Society of Australia and,
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