Risk of influenza-like illness in an acute health care setting during community influenza epidemics in 2004-2005, 2005-2006, and 2006-2007: a prospective study.
BACKGROUND
The person-to-person transmission of influenza-like illness (ILI) and influenza has been described mostly in long-term care units. Studies in acute hospital settings are rare and mostly retrospective.


METHODS
We prospectively estimated the relative risk (RR) of hospital-acquired (HA) ILI during hospitalization according to in-hospital exposures to contagious individuals. Surveillance of ILI and laboratory-confirmed influenza was undertaken at Edouard Herriot Hospital (1100 beds) during 3 influenza seasons. A total of 21 519 patients and 2153 health care workers (HCWs) from 2004 to 2007 were included. The RR of HA-ILI in patients was calculated according to exposure to other contagious patients and HCWs.


RESULTS
For patients exposed to at least 1 contagious HCW compared with those with no documented exposure in the hospital, the RR of HA-ILI was 5.48 (95% confidence interval [CI], 2.09-14.37); for patients exposed to at least 1 contagious patient, the RR was 17.96 (95% CI, 10.07-32.03); and for patients exposed to at least 1 contagious patient and 1 contagious HCW, the RR was 34.75 (95% CI, 17.70-68.25).


CONCLUSIONS
Hospitalized patients exposed to potentially infectious patients and HCWs with ILI inside the hospital are at greater risk for HA-ILI. Such results identify priorities regarding preventive measures for seasonal or pandemic influenza.
UMR, Université de Lyon, Centre National de la Recherche Scientifique, France. philippe.vanhems@chu-lyon.fr
Philippe
P
Vanhems
Nicolas
N
Voirin
Sylvain
S
Roche
Vanessa
V
Escuret
Corinne
C
Regis
Christine
C
Gorain
Silène
S
Pires-Cronenberger
Marine
M
Giard
Bruno
B
Lina
Fatiha
F
Najioullah
Béatrice
B
Barret
Laurence
L
Pollissard
Sandra
S
David
Marie-Noelle
MN
Crozet
Brigitte
B
Comte
Bernard
B
Hirschel
René
R
Ecochard
D000208:Acute Disease; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003428:Cross Infection / Q000453:epidemiology* / Q000635:transmission; D058872:Epidemics / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007251:Influenza, Human / Q000453:epidemiology* / Q000635:transmission; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012111:Residence Characteristics / Q000706:statistics & numerical data*; D012306:Risk