Condom distribution in jail to prevent HIV infection.

To determine if a structural intervention of providing one condom a week to inmates in the Los Angeles County Men's Central Jail MSM unit reduces HIV transmissions and net social cost, we estimated numbers of new HIV infections (1) when condoms are available; and (2) when they are not. Input data came from a 2007 survey of inmates, the literature and intervention program records. Base case estimates showed that condom distribution averted 1/4 of HIV transmissions. We predict .8 new infections monthly among 69 HIV-negative, sexually active inmates without condom distribution, but .6 new infections with condom availability. The discounted future medical costs averted due to fewer HIV transmissions exceed program costs, so condom distribution in jail reduces total costs. Cost savings were sensitive to the proportion of anal sex acts protected by condoms, thus allowing inmates more than one condom per week could potentially increase the program's effectiveness.