  Preventing infectious disease like flu from spreading to large communities is
one of the most important issues for humans. One effective strategy is
voluntary vaccination, however, there is always the temptation for people
refusing to be vaccinated because once herd immunity is achieved, infection
risk is greatly reduced. In this paper, we study the effect of social impact on
the vaccination behavior resulting in preventing infectious disease in
networks. The evolutionary simulation results show that the social impact has
both positive and negative effects on the vaccination behavior. Especially, in
heterogeneous networks, if the vaccination cost is low, the behavior is more
promoted than the case without social impact. In contrast, if the cost is high,
the behavior is reduced compared to the case without social impact. Moreover,
the vaccination behavior is effective in heterogeneous networks more than in
homogeneous networks. This implies that the social impact puts people at risk
in homogeneous networks. We also evaluate the results from the social cost
related to the vaccination policy.
