Informing optimal environmental influenza interventions: how the host, agent, and environment alter dominant routes of transmission.
Influenza can be transmitted through respirable (small airborne particles), inspirable (intermediate size), direct-droplet-spray, and contact modes. How these modes are affected by features of the virus strain (infectivity, survivability, transferability, or shedding profiles), host population (behavior, susceptibility, or shedding profiles), and environment (host density, surface area to volume ratios, or host movement patterns) have only recently come under investigation. A discrete-event, continuous-time, stochastic transmission model was constructed to analyze the environmental processes through which a virus passes from one person to another via different transmission modes, and explore which factors increase or decrease different modes of transmission. With the exception of the inspiratory route, each route on its own can cause high transmission in isolation of other modes. Mode-specific transmission was highly sensitive to parameter values. For example, droplet and respirable transmission usually required high host density, while the contact route had no such requirement. Depending on the specific context, one or more modes may be sufficient to cause high transmission, while in other contexts no transmission may result. Because of this, when making intervention decisions that involve blocking environmental pathways, generic recommendations applied indiscriminately may be ineffective; instead intervention choice should be contextualized, depending on the specific features of people, virus strain, or venue in question.
Department of Epidemiology, University of Michigan, Ann Arbor, Michigan, United States of America.
Ian H
IH
Spicknall
James S
JS
Koopman
Mark
M
Nicas
Josep M
JM
Pujol
Sheng
S
Li
Joseph N S
JN
Eisenberg
D019295:Computational Biology / Q000379:methods*; D003198:Computer Simulation; D004781:Environmental Exposure; D054884:Host-Pathogen Interactions / Q000502:physiology*; D006801:Humans; D007251:Influenza, Human / Q000635:transmission*; D008954:Models, Biological; D012044:Regression Analysis; D017201:Virus Shedding