Limited vaccine availability and the potential for resistance to antiviral medications have led to calls for establishing the efficacy of non-pharmaceutical measures for mitigating pandemic influenza. Our objective was to examine if the use of face masks and hand hygiene reduced rates of influenza-like illness (ILI) and laboratory-confirmed influenza in the natural setting. A cluster-randomized intervention trial was designed involving 1,178 young adults living in 37 residence houses in 5 university residence halls during the 2007–2008 influenza season. Participants were assigned to face mask and hand hygiene, face mask only, or control group during the study. Discrete-time survival models using generalized estimating equations to estimate intervention effects on ILI and confirmed influenza A/B infection over a 6-week study period were examined. A significant reduction in the rate of ILI was observed in weeks 3 through 6 of the study, with a maximum reduction of 75% during the final study week (rate ratio [RR] = 0.25, [95% CI, 0.07 to 0.87]). Both intervention groups compared to the control showed cumulative reductions in rates of influenza over the study period, although results did not reach statistical significance. Generalizability limited to similar settings and age groups. Face masks and hand hygiene combined may reduce the rate of ILI and confirmed influenza in community settings. These non-pharmaceutical measures should be recommended in crowded settings at the start of an influenza pandemic. Trail Registration Clinicaltrials.gov NCT00490633
References
[1]
Aiello AE, Coulborn RM, Aragon TJ, Baker MG, Burrus BB, et al. (2010) Research findings from nonpharmaceutical intervention studies for pandemic influenza and current gaps in the research. Am J Infect Control 38: 251–258.
[2]
Aiello AE, Murray GF, Perez V, Coulborn RM, Davis BM, et al. (2010) Mask use, hand hygiene, and seasonal influenza-like illness among young adults: a randomized intervention trial. J Infect Dis 201: 491–498.
[3]
Hayes RJ, Bennett S (1999) Simple sample size calculation for cluster-randomized trials. Int J Epidemiol 28: 319–326.
[4]
Cohen S, Kamarck T, Mermelstein R (1983) A global measure of perceived stress. J Health Soc Behav 24: 385–396.
[5]
Ohmit SE, Victor JC, Rotthoff JR, Teich ER, Truscon RK, et al. (2006) Prevention of antigenically drifted influenza by inactivated and live attenuated vaccines. N Engl J Med 355: 2513–2522.
[6]
Donner A, Klar N (1994) Cluster Randomization Trials: Theory and Application. J Stat Plan Inference 42: 37–56.
[7]
Donner A (1989) Statistical methods in opthalmology: An Adjusted chi-square approach. Biometrics 45: 605–611.
[8]
Donner A, Donald A (1988) The statistical analysis of multiple binary measurements. J Clin Epidemiol 41: 899–905.
[9]
Piantadosi S (2005) Clinical Trials: A Methodologic Perspective. New York: Wiley & Sons.
[10]
Allison PD (1982) Discrete-time methods for the analysis of event histories. Sociol Methodol 13: 61–98.
[11]
Zeger SL, Liang KY (1986) Longitudinal data analysis for discrete and continuous outcomes. Biometrics 42: 121–130.
[12]
Jefferson T, Foxlee R, Del Mar C, Dooley L, Ferroni E, et al. (2008) Physical interventions to interrupt or reduce the spread of respiratory viruses: systematic review. BMJ 336: 77–80.
[13]
Cowling BJ, Chan K-H, Fang VJ, Cheng CKY, Fung ROP, et al. (2009) Facemasks and Hand Hygiene to Prevent Influenza Transmission in Households: A Randomized Trial. Ann Intern Med 151:
[14]
MacIntyre CR, Cauchemez S, Dwyer DE, Seale H, Cheung P, et al. (2009) Face Mask Use and Control of Respiratory Virus Transmission in Households. Emerg Infect Dis 15: 233–241.
[15]
Larson EL, Ferng YH, Wong-McLoughlin J, Wang S, Haber M, et al. (2010) Impact of non-pharmaceutical interventions on URIs and influenza in crowded, urban households. Public Health Rep 125: 178–191.
[16]
Canini L, Andreoletti L, Ferrari P, D'Angelo R, Blanchon T, et al. (2010) Surgical mask to prevent influenza transmission in households: a cluster randomized trial. PLoS ONE 5: e13998.
[17]
Cowling BJ, Zhou Y, Ip DK, Leung GM, Aiello AE (2010) Face masks to prevent transmission of influenza virus: a systematic review. Epidemiol Infect 138: 449–456.
[18]
Lau JTF, Griffiths S, Choi K-c, Lin C (2010) Prevalence of preventive behaviors and associated factors during early phase of the H1N1 influenza epidemic. Am J Infect Control 38: 374–380.
[19]
Thursky K, Cordova SP, Smith D, Kelly H (2003) Working towards a simple case definition for influenza surveillance. J Clin Virol 27: 170–179.
[20]
Mitchell T, Dee DL, Phares CR, Lipman HB, Gould LH, et al. (2011) Non-pharmaceutical interventions during an outbreak of 2009 pandemic influenza A (H1N1) virus infection at a large public university, April–May 2009. Clin Infect Dis 52: Suppl 1S138–145.
