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Social imitation dynamics of vaccination driven by vaccine effectiveness and beliefs

Fig 3

Hysteresis and sensitivity of vaccination dynamics in lattice populations.

(A) and (B) depict the hysteresis loops, represented by the descending and ascending paths of the population’s equilibrium vaccination level, in response to variations in the relative cost of vaccination, c, and vaccine effectiveness, ε, respectively. Overall, the critical parameter region where the hysteresis occurs depends on specific model parameter choices. The spatial population is highly sensitive to changes in and abruptly transitions between complete opt-out and universal coverage of vaccination. (C) and (D) show spatial snapshots of population states along the descending and ascending paths of Fig 3A for a fixed c = 0.015, respectively. The color codes of individuals are the same as in Fig 1: Blue represents individuals who were vaccinated and remained healthy during the season, yellow represents individuals who were vaccinated but still became infected, grey represents individuals who were unvaccinated yet remained healthy, and red represents individuals who were unvaccinated and became infected. Parameters: Square lattice with the von Neumann neighborhood, infection seeds I₀ = 30, initial number of vaccinated , disease transmission rate , recovery rate , intensity of selection K = 1. (A) effectiveness . (C) (D): c = 0.015, . Simulation results are averaged over 150 independent runs.

doi: https://doi.org/10.1371/journal.pcbi.1013586.g003