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Local risk perception enhances epidemic control

Fig 4

Vaccination decisions vary with degree.

(A) For each degree class, we graph the proportion of individuals that vaccinate (top) along with the epidemiological situation at the time a node chooses to vaccinate in terms of the number of its infected neighbors (middle) and the overall disease prevalence in the population (bottom). Epidemiological risks—the chances of both becoming infected and infecting others—generally increase with degree. The local count strategy (light blue) is the only strategy for which the probability of vaccinating consistently increases with risk. Compared to the two other strategies, high degree individuals vaccinate earlier in terms of both local and global disease prevalence and, consequently, are less likely to become infected. (B) The number of individuals infected in each degree class under each decision strategy. The top of the curve indicates the number of individuals in each degree class (i.e., the underlying degree distribution) on a log scale. For each degree class, the stacked values indicate the expected number of individuals infected under the various strategies. The top of the gray area indicates the expected number of infections in the baseline scenario without vaccines; red indicates individuals expected to remain uninfected. Generally, local count has the lowest expected attack rate (light blue), followed by local prevalence (dark blue), and finally global prevalence. This ranking does not hold for the lowest degree individuals; instead, local prevalence has a lower expected attack rate than local count, as indicated by the dark blue line cutting through the light blue region. For all graphs, values are averages across 500 simulations, assuming R0 = 5.

Fig 4