Infection Control & Hospital Epidemiology

Original Articles

Importance of Employee Vaccination against Influenza in Preventing Cases in Long-Term Care Facilities

Aaron M. Wendelboea1a2 c1, Catherine Averya2, Bernardo Andradea3, Joan Baumbacha2 and Michael G. Landena2

a1 Epidemic Intelligence Service, Centers for Disease Control and Prevention, Atlanta, Georgia

a2 Epidemiology and Response Division, New Mexico Department of Health, Santa Fe, New Mexico

a3 Department of Biostatistics and Epidemiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma

Abstract

Objective. Employees of long-term care facilities (LTCFs) who have contact with residents should be vaccinated against influenza annually to reduce influenza incidence among residents. This investigation estimated the magnitude of the benefit of this recommendation.

Methods. The New Mexico Department of Health implemented active surveillance in all of its 75 LTCFs during influenza seasons 2006-2007 and 2007-2008. Information about the number of laboratory-confirmed cases of influenza and the proportion vaccinated of both residents and direct-care employees in each facility was collected monthly. LTCFs reporting at least 1 case of influenza (defined alternately by laboratory confirmation or symptoms of influenza-like illness [ILI]) among residents were compared with LTCFs reporting no cases of influenza. Regression modeling was used to obtain adjusted odds ratios (aORs) and 95% confidence intervals (CIs) for the association between employee vaccination coverage and the occurrence of influenza outbreaks. Covariates included vaccination coverage among residents, the staff-to-resident ratio, and the proportion of filled beds.

Results. Seventeen influenza outbreaks were reported during this 2-year period of surveillance. Eleven of these were laboratory confirmed (n = 21 residents) and 6 were defined by ILI (n = 40 residents). Mean influenza vaccination coverage among direct-care employees was 51% in facilities reporting outbreaks and 60% in facilities not reporting outbreaks (P = .12). Increased vaccination coverage among direct-care employees was associated with fewer reported outbreaks of laboratory-confirmed influenza (aOR, 0.97 [95% CI, 0.95-0.99]) and ILI (aOR, 0.98 [95% CI, 0.96-1.00]).

Conclusions. High vaccination coverage among direct-care employees helps to prevent influenza in LTCFs.

(Received March 22 2011)

(Accepted May 13 2011)

Correspondence

c1 Department of Biostatistics and Epidemiology, College of Public Health, University of Oklahoma Health Sciences, 801 NE 13th Street, Room 323, Oklahoma City, OK 73104 (Aaron-Wendelboe@ouhsc.edu)