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Volume 19, Number 4—April 2013

CME ACTIVITY

Risk Factors for Influenza among Health Care Workers during 2009 Pandemic, Toronto, Ontario, Canada

Stefan P. KusterComments to Author , Brenda L. Coleman, Janet Raboud, Shelly McNeil, Gaston De Serres, Jonathan Gubbay, Todd Hatchette, Kevin C. Katz, Mark Loeb, Donald Low, Tony Mazzulli, Andrew Simor, Allison J. McGeer, Stefan P. KusterComments to Author , Brenda L. Coleman, Janet Raboud, Shelly McNeil, Gaston De Serres, Jonathan Gubbay, Todd Hatchette, Kevin C. Katz, Mark Loeb, Donald Low, Tony Mazzulli, Andrew Simor, Allison J. McGeer, and on behalf of the Working Adult Influenza Cohort Study Groupon behalf of the Working Adult Influenza Cohort Study Group
Author affiliations: Mount Sinai Hospital, Toronto, Ontario, Canada (S.P. Kuster, B.L. Coleman, D. Low, T. Mazzulli, A.J. McGeer); University of Toronto, Toronto (B.L. Coleman, J. Raboud, K.C. Katz, D. Low, T. Mazzulli, A. Simor, A.J. McGeer); Dalhousie University, Halifax, Nova Scotia, Canada (S. McNeil, T. Hatchette); Laval University Québec, Québec City, Québec, Canada (G. De Serres); Ontario Agency for Health Protection and Promotion, Toronto (J. Gubbay, D. Low); North York General Hospital, Toronto (K.C. Katz); McMaster University, Hamilton, Ontario, Canada (M. Loeb); Sunnybrook Health Sciences Centre, Toronto (A. Simor).; Mount Sinai Hospital, Toronto, Ontario, Canada (S.P. Kuster, B.L. Coleman, D. Low, T. Mazzulli, A.J. McGeer); University of Toronto, Toronto (B.L. Coleman, J. Raboud, K.C. Katz, D. Low, T. Mazzulli, A. Simor, A.J. McGeer); Dalhousie University, Halifax, Nova Scotia, Canada (S. McNeil, T. Hatchette); Laval University Québec, Québec City, Québec, Canada (G. De Serres); Ontario Agency for Health Protection and Promotion, Toronto (J. Gubbay, D. Low); North York General Hospital, Toronto (K.C. Katz); McMaster University, Hamilton, Ontario, Canada (M. Loeb); Sunnybrook Health Sciences Centre, Toronto (A. Simor).

Main Article

Table 3

Risk factors for symptomatic influenza infection among health care workers in acute care hospitals and non–health care workers in office settings during 2009 pandemic, Toronto, Ontario, Canada*

Risk factor OR (95% CI), adjusted† OR (95% CI), multivariable‡
Worker in acute care hospital 0.49 (0.19–1.27) 0.47 (0.17–1.32)
Age, y, per 10 y increase 1.08 (0.76–1.54) NA
Female sex 1.03 (0.30–3.56) NA
Recipient of A(H1N1)pdm09 vaccine§ 0.28 (0.03–2.28)¶ 0.34 (0.04–2.85)
Weekly percentage of specimens yielding influenza per 5% increase
1.49 (1.28–1.73)#
1.36 (1.13–1.63)
Potential exposure conditions
Hand-to-face habits** 3.09 (1.12–8.52) NA
Child <18 y in household 3.13 (1.21–8.07) NA
Contact with family member with ARI in prior wk 5.51 (1.81–16.76) 6.89 (2.17–21.84)
Contact with co-worker with ARI in prior wk 0.77 (0.10–6.16) NA
Household crowding index >1†† 1.99 (0.79–5.05) NA
Public transit >8 trips per wk 0.62 (0.22–1.76) NA

*Constant and time-dependent risk factors for symptomatic influenza infection (positive nasal swab specimen) in 732 primary contacts of the Influenza Cohort Study followed during June 2009–April 2010, Toronto, Ontario, Canada. OR, odds ratio; NA, not applicable; A(H1N1)pdm09: pandemic influenza A(H1N1) 2009 virus; ARI: acute respiratory illness.
†Adjusted for receipt of A(H1N1)pdm09 vaccine and weekly percentage of specimens yielding influenza.
‡Multivariable model including all variables with ORs listed below.
§Participants who had acquired A(H1N1)pdm09 <7 d after vaccination were considered unprotected.
¶Adjusted for weekly percentage of specimens yielding influenza only.
#Unadjusted.
**Defined as biting one’s nails or cuticles, habitually putting one’s fingers in his or her mouth or nose.
††Household crowding index is defined as number of persons per household divided by the number of bedrooms.

Main Article

1Additional members of the Working Adult Influenza Cohort Study Group are listed at the end of this article.

1Additional members of the Working Adult Influenza Cohort Study Group are listed at the end of this article.

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