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April 1988

The Roles of Vaccination and Amantadine Prophylaxis in Controlling an Outbreak of Influenza A (H3N2) in a Nursing Home

Author Affiliations

From the Influenza Branch, Division of Viral Diseases, Center for Infectious Diseases, Centers for Disease Control (Ms Arden and Drs Patriarca, Lui, Harmon, and Kendal), the Veterans Administration Medical Center (Drs Fasano and Rimland), and the Department of Medicine, Emory University School of Medicine (Dr Rimland), Atlanta. Dr Patriarca is now with the Division of Immunization, Centers for Disease Control, Atlanta. Dr Fasano is now with the Department of Pediatrics, The Johns Hopkins University School of Medicine, Baltimore. Dr Lui is now with the Center for Environmental Health, Centers for Disease Control, Atlanta.

Arch Intern Med. 1988;148(4):865-868. doi:10.1001/archinte.1988.00380040105016

• An outbreak caused by influenza A/Philippines/2/82 (H3N2)—like viruses occurred in a partially vaccinated nursing home population in January 1985. During the first six days of the outbreak, 14 (25%) of 55 residents developed influenzalike illness. The risk of illness was most strongly associated with undetectable levels of antibody against the epidemic strain, with unvaccinated case-patients having more severe illnesses and a higher rate of hospitalization than vaccinated case-patients (5/8 vs 0/6). During the period of amantadine hydrochloride prophylaxis (100 mg/d) from days 7 to 35, only two (5%) of the remaining 41 residents became ill, even though 11 (27%) had no detectable antibody. Serum amantadine levels obtained on day 35 ranged from 117 to 737 ng/mL (mean 309 ng/mL), similar to therapeutic levels documented in younger adults who have taken the standard regimen of 200 mg/d; there were few clinically significant side effects. These findings illustrate the benefits of influenza vaccination and support the use of amantadine hydrochloride at a dosage of 100 mg daily for outbreak control among elderly persons.

(Arch Intern Med 1988;148:865-868)

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