Figure 9
Compartmental structure in each subpopulation in the intervention scenario. A modified Susceptible-Latent-Infectious-Recovered model is considered, to take into account asymptomatic infections, traveling behavior while ill, and use of antiviral drugs as a pharmaceutical measure. In particular, infectious individuals are subdivided into: asymptomatic (Infectious_a), symptomatic individuals who travel while ill (Infectious_s_t), symptomatic individuals who restrict themselves from travel while ill (Infectious_s_nt), symptomatic individuals who undergo the antiviral treatment (Infectious_AVT). A susceptible individual interacting with an infectious person may contract the illness with rate beta and enter the latent compartment where he/she is infected but not yet infectious. The infection rate is rescaled by a factor ra in case of asymptomatic infection [41, 46], and by a factor rAVT in case of a treated infection. At the end of the latency period, of average duration equal to eps -1, each latent individual becomes infectious, showing symptoms with probability 1-p a , whereas becoming asymptomatic with probability p a [41, 46]. Change in travelling behavior after the onset of symptoms is modeled with probability p t set to 50% that individuals would stop travelling when ill [41]. Infectious individuals recover permanently after an average infectious period mu -1 equal to 2.5 days. We assume the antiviral treatment regimen to be administered to a 30% fraction (i.e. pAVT = 0.3) of the symptomatic infectious individuals within one day from the onset of symptoms, reducing the infectiousness and shortening the infectious period of 1 day. [41, 42].