Male circumcision reduces HIV risk by as much as 60%

Three clinical trials in Africa found that adult male circumcision reduced the risk of men acquiring HIV infection from heterosexual sex by 51-60%.

While adult male circumcision may also have a role to play in preventing HIV transmission in the US, say scientists at the US Centers for Disease Control (CDC) in a paper in PLoS Medicine, "the extent of this role on a population basis is unknown."

Patrick Sullivan (Division of HIV/AIDS Prevention,CDC) and colleagues argue that the potential impact of adult male circumcision on HIV transmission rates in the US is hard to predict, given the many differences between the underlying HIV epidemics in Africa and the US, differences in the prevalence of male circumcision in Africa and the US, and the considerable gaps in knowledge that exist regarding the potential impact of circumcision on HIV transmission by male, male sex.

"The HIV epidemics in Africa are substantially different from the US epidemic," they say. The predominant mode of HIV transmission in Africa is heterosexual sex whereas the US has a concentrated HIV epidemic with most sexual transmission occurring among men who have sex with men (MSM). The African trials did not study MSM. While some observational studies have suggested that circumcised MSM in the US may have a decreased risk of HIV infection, say the authors, it is impossible to draw firm conclusions from such observational research, which is prone to bias.

Adult male circumcision will likely have the largest impact in populations where circumcision has been rare, they say. Yet in the US circumcision is already very common, hospital discharge data show that in 1999 around two thirds of all newborn boys were circumcised.

Nevertheless, based on the data from the three African clinical trials, Sullivan and colleagues conclude that "it is likely that circumcision will decrease the probability of a man acquiring HIV via penile, vaginal sex with an HIV-infected woman in the US." Until public health recommendations are available for the US, they say, "some sexually active men may consider circumcision as an additional HIV prevention measure, but should do so only in consultation with their physician or health care provider, and with a clear understanding of the costs and risks of circumcision and the need to continue use of other, proven prevention measures (e.g., reducing the numbers of sex partners and using condoms consistently and correctly). Men who choose to be circumcised should also be counseled about the importance of refraining from sexual intercourse following circumcision, until wound healing is complete. Men should also understand that male circumcision has only proven effective in reducing the risk of infection through insertive vaginal sex."