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Volume 8, Number 8—August 2002


Serologic Evidence of H1 Swine Influenza Virus Infection in Swine Farm Residents and Employees

Christopher W. Olsen*Comments to Author , Lynnette Brammer†, Bernard C. Easterday*, Nancy Arden†‡, Ermias D. Belay†, Inger Baker†, and Nancy J. Cox†
Author affiliations: *University of Wisconsin-Madison, Madison, Wisconsin, USA; †Centers for Disease Control and Prevention, Atlanta, Georgia, USA; ‡College of Medicine, Texas A & M University, College Station, Texas, USA;

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Table 3

Variables associated with seropositivity to swine influenza viruses among the farm participants and the statistical strength of these associations a

Variable HI titer >40b HI titer >80b
Being a farm owner p=0.04 p=0.02
Being a farm owner or the family member of a farm owner p=0.03 p=0.02
Living on a swine farm (p = 0.07) p=0.04
Going into a swine barn >4 days/week (p = 0.12) p=0.04
Age >50 yrs p=0.02 p=0.03
Having received the swine flu vaccine in 1976–77 p=0.02 (p = 0.44)
Ever having received any influenza virus vaccine p=0.03 (p = 0.19)

aP values determined by chi-square or two-sided Fisher’s exact analyses; p values >0.05 cut-off for significance are shown in parentheses.
bTo either swine virus. Abbreviation used: HI, hemagglutination-inhibition.

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