Planning horizon affects prophylactic decision-making and epidemic dynamics

Luis G. Nardin; Craig R. Miller; Benjamin J. Ridenhour; Stephen M. Krone; Paul Joyce; Bert O. Baumgaertner

Introduction infected (e.g. wearing a mask, washing hands, etc.). Agents in the infectious state I are infected 73 and infective, while those in the recovered state R are immune to and do not transmit disease. 74 The transition between states is captured with the state-transition diagram shown in Fig. 1 . For 75 reference, all the parameters and variables in the SPIR model are listed and defined in Table 1 . S, P, I, and R represent the four epidemiological states an agent can be in: Susceptible, Prophylactic, Infectious, and Recovered, respectively. The parameters over the transitions connecting the states represent the probability per time step that agents in one state move to an adjacent state: i is the proportion of infectious agents in the population; bS and bP are the respective probabilities that an agent in state S or P, encountering an infectious agent I, becomes infected; g is the recovery probability; d is the behavioral decision making probability; and W(i) is an indicator function returning value 1 when the utility of being prophylactic is greater than the utility of being susceptible and 0 otherwise (see details in Behavioral Decision Model). This sub-model assumes that in each time step, three types of events occur: (i) interactions Proportion of susceptible agents in the population. p