Sutton's Law and AIDS prevention in Israel.

Calculation of risk-group-specific rates of HIV infection in the adult population of Israel results in the identification of four groups comprising, in total, less than 2% of the population, each of which carries a relative risk of infection of 500 or more. An estimated 90% of infections to date have occurred in these four groups. Rather than dissipate HIV prevention efforts over the entire population, 98% of whom are at zero or near-zero risk of infection, efforts to prevent HIV transmission should concentrate on the groups whose relative risk is enormously high and in whom there is the greatest potential for preventing further transmission.