Fig. 3: The optimal solution and its stability across α values. | Communications Medicine

Fig. 3: The optimal solution and its stability across α values.

From: A game theoretic approach identifies conditions that foster vaccine-rich to vaccine-poor country donation of surplus vaccines

Fig. 3

The optimal solution and its stability depend on the values of the parameters \({v}_{{{\max }}}\), λ, and α. Each panel characterizes a different value of α: a \(\alpha =0.1\). b \(\alpha =0.2\). c \(\alpha =0.3\). \(N=6\) in all panels. Each colored rectangle on the top panel represents the solution for the corresponding values of λ and \({v}_{{{\max }}}\). In regions I, II, and III (yellow shades), \({s}_{i}=2\) by all vaccine-rich countries is optimal. In regions IV, V, and VI (blue shades), \({s}_{i}=1\) by all countries is optimal. In region VII (black), \({s}_{i}=0\) by all countries is optimal. One notable observation is that if α (the unavoidable fraction of the cost of an outbreak, given surplus doses) is smaller, then it is less worthwhile to donate, and the range of parameters that renders donations advantageous is narrower.

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