Required antiviral stockpile and ratio of the total clinical infections. Required stockpile of antiviral drugs (relative to S
0) as a function of the treatment level for (a) R
0 = 1.5; and (b) R
0 = 2.5. Ratio of the total number of clinical infections to S
0 as a function of the treatment level for: (c) R
0 = 1.5; and (d) R
0 = 2.5. Solid curves correspond to the case where resistance is absent, and dashed curves represent the scenario in which resistant viruses with HTF are present.