Tradeoffs involving coupling, time delay and available vaccine represented by contours of combined final epidemic size.

<p>The mean final epidemic size for two coupled cities 〈<i>E</i>〉 is plotted as a function of fractional vaccine allocation to city B and coupling <i>f</i>_AB for varying amounts of available vaccine at <i>τ</i> = 1 day (panel A) and <i>τ</i> = 10 days (panel B). City A has 39 initial susceptibles and 1 infective; city B has 40 initial susceptibles. The recovery rate <i>γ</i> = 0.15 and the reproductive number <i>r</i>₀ = 2.