Figure 3.

Illustration of different run-out scenarios. (a) Stockpile of 10% and R₀=1.5. There are precisely two values of AV coverage, marked α₁ and α₂, such that U(α)=M. Run-out may be avoided by α<α₁ or by α>α₂. (b) Stockpile of 30% and R₀=2, 3. Here R₀ is sufficiently large for the antiviral usage U(α) to be monotonically increasing with respect to α. Run-out can be avoided only by a sufficiently low AV coverage.