How Did Circumcision Prevent HIV in Clinical Trials in Africa ... And What Does It Mean for the United States?
Educational Briefing Paper for U.S. AIDS Communities Based on Information Available as of March 29, 2007
Recent research shows that circumcision1 could be an effective new HIV prevention tool, especially in areas of the world with high HIV prevalence and low rates of circumcision. This promising news is clearly significant for sub-Saharan Africa. It is still unclear what this data could mean for HIV prevention strategies in the United States, where the epidemic is severe within specific communities, but is different from the epidemic in hard-hit regions of Africa where AIDS is common among the general population.
There is a lot of new and important data on circumcision, and much of it raises more questions than answers when we consider what it may mean for the epidemic in the U.S. For example, the studies in Africa mostly focused on women-to-men HIV transmission during vaginal sex -- these trials did not address whether circumcision protects men who have sex with each other, or if it is protective for men or women during anal sex. They also did not yet provide answers about the role of circumcision in protecting women during vaginal sex. But in the U.S., nearly half of all infections occur through male-to-male sexual activity, and the vast majority of heterosexual transmission in the U.S. is from men to-women.
While new data on male circumcision as an HIV prevention tool are very promising for some settings, particularly in the developing world, it is still unclear how this data could -- or should -- impact HIV prevention strategies in the United States.
How Is Circumcision Done in Adult Men, and How Can It Reduce Transmission of HIV From Women to Men?
Circumcision is a one-time procedure that could help decrease, but not eliminate a man's risk of acquiring HIV during vaginal sex, possibly for the rest of his life. Because it does not eliminate the risk of HIV, some circumcised men in the African studies did become HIV-positive, and many HIV-positive men in the U.S. are circumcised.
Adult circumcision requires surgically removing the foreskin of the penis (Infant circumcision is a simpler procedure, which does not involve stitches). The foreskin contains "target cells" that HIV infects during the initial stages of exposure. After it is removed during circumcision, the remaining skin develops a different, protective surface, which is called keratinized skin. This skin has fewer target cells.
Keratinization is thought to be one of the reasons why circumcision reduces men's risk of acquiring HIV during vaginal sex. Another reason may be that circumcision appears to reduce rates of genital ulcer disease, a condition that can increase the risk of getting or transmitting HIV.
Overview of Circumcision Studies
Observations of the Potential Protective Effect of Circumcision
Over the years, researchers have observed that rates of HIV were lower in African and Asian populations where circumcision was common, and that there were much higher rates of HIV in countries where fewer men were circumcised.
In the U.S., two different observational studies on gay men and other men who have sex with men (MSM) showed that uncircumcised men were twice as likely to be, or become, HIV-positive. Another study observed that uncircumcised heterosexual men in an urban STD clinic had a 3.5-fold higher risk of HIV infection, but the results were not statistically significant.
However, observational studies like these did not prove a connection between circumcision and reduced risk of HIV infection -- there could be other explanations for the apparent connection. The next stage of research was to conduct large-scale, randomized trials to investigate this theory.
Circumcision as an HIV prevention intervention for men who have sex with women:
Three randomized clinical studies in sub-Saharan Africa have shown that circumcision of males aged 15-48 can reduce their risk of acquiring HIV from women through vaginal sex by 50-60%. All three studies -- conducted in South Africa, urban Kenya and rural Uganda -- ended randomization early, after each study showed strong findings of a protective benefit from circumcision. All men in the trials were also given screening and treatment for sexually transmitted infections, condoms, and risk reduction counseling.
Most HIV vaccine trials aim for a 50% protection rate. The results of the circumcision trials showing 50-60% reduction in HIV risk for men are very significant -- and comparable to our current expectations of an HIV vaccine. We still need a vaccine that can protect women, men and babies, but circumcision is available today while an effective HIV vaccine is still at least ten years away.
Circumcision as an HIV prevention intervention for women who have sex with HIV-positive male partners:
A related study in Rakai, Uganda was designed to evaluate whether HIV-positive men with T cell counts over 350 who undergo circumcision are less likely to transmit HIV to their female sexual partners. Unfortunately, the trial could not move forward because of difficulty recruiting enough participants, and could not effectively answer the trial question: are HIV-positive men who become circumcised less likely to transmit HIV to their female sexual partners?
It is important to note that we do not yet have enough data to conclude whether having a male partner who is circumcised has any direct protective benefit for women. Nonetheless, reducing the number of new infections among men would probably mean that fewer women would be exposed to HIV over time.
Early analysis from this study suggested, but did not prove, that the female sexual partners of newly circumcised men could be at increased risk of HIV if they had sex before the wound completely healed. However, this data was not statistically significant and results could change with further research and analysis.
Still, these early data stress the importance of clearly communicating the risks and benefits of adult circumcision, including the need to abstain from sex for at least one month following the procedure to allow the wound to fully heal. Researchers are continuing to monitor the HIV-positive men who had already enrolled in the trial and been circumcised, as well as their female partners, to determine if circumcision could provide a long-term protective benefit to women.
Circumcision in the U.S.
Most males in the U.S. are circumcised as newborns. However, the national rate of infant circumcision has been declining. The National Hospital Discharge Survey (NHDS) reported that newborn circumcision had dropped from 65% in 1999 to 57.4% in 2004.
There are also dramatic differences in circumcision rates between geographic regions. While almost 80% of male newborns in the Midwest were circumcised in 2004, only one-third of newborn males in the West were circumcised during that same year. Many factors play into these regional disparities, including immigration patterns, changing cultural norms, the religious and ethnic make-up of areas, and state differences in Medicaid coverage for circumcision.
Unfortunately, the only data available on male circumcision broken down by race and ethnicity is fifteen years old. In 1992, the National Health and Social Life Survey reported that 77% of men reported being circumcised, of whom 81% identified as white, 65% as African American, and 54% as Latino.2
In 1999, the American Academy of Pediatrics stopped recommending routine circumcision. Since then, sixteen states have dropped Medicaid coverage for circumcisions that are not considered medically necessary. Half of these states are in the West, where circumcision rates are the lowest.
States that do not provide Medicaid coverage of routine infant circumcision include: Arizona, California, Florida, Idaho, Louisiana, Maine, Minnesota, Mississippi, Missouri, Montana, Nevada, North Carolina, North Dakota, Oregon, Utah, and Washington.
HIV/AIDS and Circumcision in the U.S.
Right now, the only solid evidence we have on circumcision is that it reduced the risk of men in the sub-Saharan African trials getting HIV during vaginal sex. Female-to-male transmission is a much more common mode of transmission in Africa than in the U.S. In the U.S., nearly half (47%) of all new cases diagnosed in 2004 occurred in MSM. 33% of newly-diagnosed people were exposed through heterosexual contact3 -- most of whom were women. In the U.S., the vast majority of heterosexual HIV transmission is from men-to-women, not women-to-men. It is also believed that some men who report contracting HIV from women may do so because of the stigma around male-to-male sex.
The following table lists states with the highest rates of new AIDS cases and shows the percentages of new infections due to male-to-male and heterosexual contact. Data on the gender of individuals exposed during heterosexual sexual contact were not available.
Reported AIDS Cases Among Adults and Adolescents, by Transmission Category, Cumulative through 2005
Nearly all circumcisions in the U.S. are performed on infants. And we don't know which of them will be gay men, heterosexuals, or non-gay-identified MSM. We do know, however, that there are much higher rates of HIV in some communities in the U.S., most notably the African American community. Thus, it may be possible to advise parents about the impact of circumcision on their children's lifetime risk of HIV, using mathematical models that incorporate racial/ethnic data.
We also need further research to determine whether circumcision is protective against HIV during anal sex, including for both male and female partners. This research should explore whether insertive partners (tops) are less likely to get HIV if they are circumcised, as well as any possible protection for their receptive partners (bottoms).
The CDC is currently examining the potential role of circumcision as an HIV prevention intervention in the U.S., and plans to convene a stakeholder consultation in April or May 2007 in order to develop a research agenda and potential recommendations for circumcision in the U.S.
Summary: Explaining the Circumcision Data in the Context of the U.S. Epidemic
Current data show that circumcision dramatically reduced the risk of HIV for men from vaginal sex in trials in three countries in Africa, but does not tell us about the protective benefits during anal sex. A majority of new infections in the U.S. are due to male-to-male sex, and studies with gay and other MSM communities should be a top priority for the U.S. research agenda. The second most common mode of transmission is from men to women, and we do not currently have enough information about the potential benefit for women if their male partners are circumcised.
The studies in Africa took place in areas with high prevalence and low circumcision rates. In the U.S., there are many disparities between communities in HIV risk and circumcision rates. We should begin to identify communities, such as African American and Latino communities, with high HIV risk and low circumcision rates, where implementing circumcision may have an impact. These communities could serve as future circumcision study sites in the U.S. and could be prioritized for small pilot programs on circumcision as an HIV prevention tool.
However, given the differences between the U.S. and African epidemics, it may indeed be that the projected impact of circumcision is negligible in the United States, or may be significant only in limited settings.
* Within both Africa and the U.S., there are many diverse communities and varying epidemics.
Policy Issues to Consider on Circumcision, HIV and the United States AIDS Epidemic
Community education and access to information
Research needs and data collection
For Further Information
Male Circumcision and Risk for HIV Transmission: Implications for the United States (CDC)
New Data on Male Circumcision: Policy and Programme Implications (World Health Organization)
Advocacy Materials from the AIDS Vaccine Advocacy Coalition
or contact CHAMP at 212-937-7955 x 5
NYC Mayor Bloomberg Raises Questions About Plans to Promote Male Circumcision as HIV Prevention Method
New Frontiers in HIV Prevention: Male Circumcision and Pre-Exposure Prophylaxis in the United States -- An Interview at CROI 2007 With Patrick Sullivan, Ph.D., and Lynn Paxton, M.D., M.P.H.
This article was provided by Community HIV/AIDS Mobilization Project.