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Volume 19, Number 4—April 2013
CME ACTIVITY - Research

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, 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 2

Results of influenza virus testing of nasal swab specimens from 732 study participants in the Influenza Cohort Study performed during 2009 pandemic, Toronto, Ontario, Canada*

Characteristic Influenza test status
No. negative or not ill, n = 712† No. positive, n = 20‡ p value
Mean age, y (± SD) 42.9 (11.3) 43.9 (9.3) 0.69
Female sex 595/712 (83.6) 16/20 (80.0) 0.76
Worker in acute care hospital
 550/712 (77.3)
 13/20 (65.0)
 0.28
Recipient of vaccine
A(H1N1)pdm09 vaccine§ 533/699 (76.3) 2/20 (10.0) <0.001
Seasonal influenza vaccine 2009–10 258/712 (36.2) 9/20 (45.0) 0.42
Seasonal influenza vaccine 2008–09
 470/696 (67.5)
 13/20 (65.0)
 0.81
Underlying health conditions
Asthma 67/702 (9.5) 2/20 (10.0) 1.00
Diabetes mellitus 26/700 (3.7) 1/20 (5.0) 0.54
Allergy to airborne irritants 284/646 (44.0) 11/18 (61.1) 0.15
Current smoker
 63/704 (9.0)
 3/20 (15.0)
 0.42
Potential exposure conditions
Hand-to-face habits 337/705 (47.8) 14/20 (70.0) 0.05
Wearing of prescription eyeglasses 493/709 (69.5) 12/20 (60.0) 0.36
Reusable water bottle use >1×/ wk 307/705 (43.6) 6/20 (30.0) 0.23
Public transit >8 trips per week 236/706 (33.4) 5/20 (25.0) 0.43
Group gathering attendance >1× 655/710 (92.3) 19/20 (95.0) 1.00
Face-to-face contacts/d, median (IQR) 10 (5, 20) 15 (8, 20) 0.53
Household crowding index >1# 233/697 (33.4) 10/20 (50.0) 0.12
Children in workplace 68/705 (9.7) 3/20 (15.0) 0.43
Child <5 y in household 83/712 (11.7) 4/20 (20.0) 0.28
Child <18 y in household 258/712 (36.2) 13/20 (65.0) 0.009
Child in household attends day care 87/699 (12.5) 6/20 (30.0) 0.03

*Data are no./total (%) unless otherwise specified. A(H1N1)pdm09, pandemic influenza A(H1N1) 2009 virus; IQR, interquartile range.
†Participants who did not report any illness or whose nasal swab samples tested negative for influenza.
‡All participants who tested positive were symptomatic.
§Participants who had acquired A(H1N1)pdm09 <7 d after vaccination were considered unprotected
¶Defined as biting one’s nails or cuticles or 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.

Page created: March 18, 2013
Page updated: March 18, 2013
Page reviewed: March 18, 2013
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