Male Circumcision for Prevention of HIV Transmission: What the New Data Mean for HIV Prevention in the United States

T hree randomized, controlled clinical trials in South Africa, Kenya, and Uganda were recently unblinded early because interim analyses concluded that circumcision of HIV-negative adult males reduced their risk for acquiring HIV infection through penile–vaginal sex [1–3]. In each trial, men who had been randomly assigned to an intervention group receiving circumcision had a lower incidence of HIV infection in up to two years of follow up, compared to men who were assigned to a control group not receiving circumcision. The estimated reduction in the risk of HIV infection ranged from 51% to 60%; per-protocol estimates of risk reduction ranged from 55% to 76%. It is now clear that male circumcision can be effi cacious for men in reducing their risk of HIV acquisition through sex with women [4]. Some experts predict that the impact of male circumcision as a biomedical intervention for HIV prevention in Africa could be large [5,6], and preparatory work has been done to establish male circumcision programs in Africa. The implications of African trials on circumcision for HIV prevention programs in the United States are less clear—despite the interest of the popular press in the idea [7]. Here, we consider the differences between the HIV epidemics in Africa and the US, the current status of male circumcision in the US, and the knowledge gaps that will need to be addressed as we consider whether male circumcision should be evaluated or implemented as a biomedical intervention to reduce sexually acquired HIV infections domestically. The results of any trial must be interpreted with the caution that inference not be extended to populations differing from the study participants in important ways. The HIV epidemics in Africa are substantially different from the US epidemic. Generalized HIV epidemics exist in many areas of Africa, and the population prevalence of HIV among adult Kenyans, Ugandans, and South Africans ranges from 6%–19% [8]. The predominant mode of HIV transmission in Africa is male–female sex. In contrast, the US has a concentrated epidemic, with most sexual transmission occurring among men who have sex with men (MSM). The general population prevalence of HIV is about 0.4% in the US [9], and only 15% of men diagnosed with HIV infection during 2005 were reported to have acquired HIV through male– female sex [10]. The association between circumcision and reduced risk for HIV acquisition is biologically plausible: the foreskin contains high concentrations of superfi cial Langerhans …