Fig. 5.

Case where ${\mathcal{R}}_0\le 1+\frac{1}{\sqrt{1-\mathit{\delta }}}$ (Case 1). Here, we set ${\mathcal{R}}_0=1.5$ and $\mathit{\delta }=0.45$. (a) Graph of the probabilities of infection among individuals who accept or reject vaccination. (b) Graph of the differences between two probabilities of infection: (1) When $C^v>{\pi }_{V,N}^{\mathrm{B}}$, there is no Nash vaccination strategy, (2) when $C^v={\pi }_{V,N}$, there is a unique Nash vaccination strategy ${\psi }_{\mathrm{NE}}$.