Hand hygiene and surface cleaning should be paired for prevention of fomite transmission

Touching contaminated surfaces might lead to the spread of pathogens, that is, the fomite transmission route. Although hand- and surface-hygiene practices are potentially important non-pharmaceutical interventions for the fomite route, the two interventions have been mostly studied separately in the literature. In this study, we develop a new conceptual model based on the law of mass action, analyze the temporal diffusion of contaminated surfaces and hands, and verify the model with simulations in an assumed norovirus outbreak in a buffet restaurant. A quantitative hygiene criterion is developed for the required frequency of surface disinfection and hand hygiene to control the fomite transmission in indoor environments. To eliminate surface contaminations, the product of pathogen-removal rates (including hygiene and natural death) on hands and surfaces must be no smaller than that of the human hand and surface contact frequency (ie, the net removal product must be non-negative). When the net removal product is negative, the number of contaminated surfaces and hands would show a logistic growth trend and finally approach the equilibrium. Our approach sheds light into how to optimize the combined use of hand hygiene and environmental decontamination for the best effectiveness under different settings.