This figure shows the cost per HIV infection averted for the Increased Monogamy scenario, as a function of annual program costs (measured as $/person/year) and program effectiveness (measured as the percentage reduction in concurrency). Costs and infections averted are discounted to the present at 3% per year. Results are shown for each of the four study countries, Swaziland (a), Tanzania (b), Uganda (c), and Zambia (d). 95% confidence intervals are indicated for each sample point.