The Expanding HIV Prevention Toolkit
In the past decade the number of HIV prevention options available to reduce the risk of HIV transmission has increased. Some of these strategies are generating a lot of excitement because they may provide an option for people who don't want to, or are unable to, use condoms. These include the following:
- Antiretroviral treatment -- which reduced the risk of HIV transmission by 96% among heterosexual serodiscordant couples in a randomized controlled trial (RCT).12
- Pre-exposure prophylaxis (PrEP) -- which reduced the risk of HIV transmission by 40 to 70% for gay men13 and heterosexual men and women14,15 in RCTs. Further analysis suggested that PrEP may have reduced HIV risk by up to 90% among those who always took their pills.13,14
- Post-exposure prophylaxis (PEP) -- which reduced the risk of HIV transmission by up to 80% in an observational study of healthcare workers exposed to HIV in the workplace.16
- Observational studies suggest that behavioural strategies such as serosorting, strategic positioning and withdrawal may slightly reduce the risk of HIV transmission.17
People who want to use, or are already using, these strategies may want to know how effective they are compared to condoms. These questions can be challenging to answer and it's important that, in our responses, we don't compare apples and oranges. For example, comparing results from different types of studies can be problematic. Some of the new prevention strategies were evaluated using an RCT while condoms were evaluated using observational studies. Comparing the results from these two kinds of studies can be problematic for a number of reasons:
- In RCTs the two groups are randomized to ensure that there are no differences between the groups other than whether or not they received the intervention. This is important because we know that each group should have similar risk behaviours and that neither group should be more or less likely to get HIV. However, in observational studies (such as those used to assess condoms), one group could be having sex more often or engaging in riskier sex. This could impact the results and make a strategy, such as condoms, appear to be less effective than they actually are.
- RCTs create "ideal" conditions that can make a strategy appear more effective than it would be in the "real world." For example, RCT participants are supported to ensure they use the strategy correctly and all participants are provided with a comprehensive package of prevention services, including STI testing and treatment, free condoms, and intensive adherence and risk-reduction counselling. By contrast, observational studies, such as those used to evaluate condoms, generally do not provide participants with additional supports. Therefore, these results may not be directly comparable to the results of RCTs.
When it comes to comparing the effectiveness of two prevention strategies, we need to pay attention to the research design used to measure that effectiveness. Most new prevention strategies, such as PrEP or treatment as prevention, have been evaluated using RCTs, which can tell us about the effectiveness of the strategy under "ideal conditions." Unfortunately, we don't know how effective condoms would be under the ideal conditions of an RCT; however, we have good reason to believe that they would be more than 80% effective when used consistently and correctly.
Implications for HIV Prevention Messaging
Although there is excitement surrounding new HIV prevention strategies, safer sex messaging and prevention counselling need to emphasize that the correct and consistent use of condoms remains the most effective method of preventing the sexual transmission of HIV (other than abstinence and long-term mutual monogamy between two people with the same HIV status).
When answering questions about the effectiveness of condoms, it's important to emphasize that they have several advantages over other options. Key messages include the following:
- If a condom is used correctly and it doesn't break, slip or leak, then it is virtually 100% protective. However, there is a still a possibility that condoms will break, slip, or leak even when used correctly. Condoms do not eliminate the risk of HIV transmission.
- Condom effectiveness does not rely on accurate knowledge of a person's HIV status, as opposed to serosorting, which requires accurate knowledge of the HIV status of both partners -- something that is often difficult to know for certain.
- Whereas the goal of some other strategies -- such as PEP, PrEP or having an undetectable viral load -- is to reduce the risk of an exposure leading to an infection, condoms prevent an exposure to HIV from occurring in the first place.
- Other prevention options may be less effective if either partner has an STI, a higher viral load or other biological factors that affect HIV risk whereas condom effectiveness is not affected by these.
- If they don't break, slip or leak, condoms can reduce the risk of HIV transmission for both anal and vaginal sex to the same level. However, the risk of HIV transmission while using PrEP or when the viral load is undetectable may be higher for anal sex than for vaginal sex. (This is because anal sex has a higher baseline risk of HIV transmission than vaginal sex.18)
- Condoms also reduce the risk of other STIs, such as gonorrhea, chlamydia, herpes and syphilis.19 Although other strategies may reduce the risk of HIV transmission, they do not reduce the risk of STI transmission. This is important because STIs can increase a person's risk of HIV transmission.20
- Condoms can reduce the risk of unintended pregnancy.
- Condoms are less expensive, more readily available and less toxic than strategies that involve antiretroviral medications, such as PEP and PrEP.
Despite the advantages of condoms, we can't ignore the important role that other prevention strategies may play in helping someone reduce their risk of HIV transmission. Condoms are not without their disadvantages and these can make it difficult for people to use them consistently and correctly. For example, condom use can be difficult to negotiate, condoms can decrease sexual pleasure and intimacy, they need to be available at the time of intercourse, they may be difficult to use when under the influence of alcohol or drugs, and they do not allow a woman to conceive. For these reasons, some people may choose to reduce their risk of HIV transmission in other ways.
HIV prevention efforts need to focus on helping people adopt prevention strategies that are appropriate to their circumstances and will be most effective for them. If people are having difficulty using condoms or are having problems with condom breakage, slippage or leakage, counselling may help them use condoms more consistently and correctly.
At the same time, alternative strategies for reducing the risk of HIV transmission may need to be discussed with these clients. When exploring other prevention options, it's important to clearly explain their limitations, factors that may decrease their effectiveness and how a person can keep their risk of HIV transmission as low as possible while using these strategies. No strategy -- including condoms -- is 100% effective; all have their limitations and can fail in different ways. Since condoms provide less than 100% protection, using other strategies in combination with condoms will help decrease a person's overall risk of HIV transmission. However, if a client or patient decreases their condom use in favour of a less protective strategy, they may be increasing their overall risk of HIV transmission.
AIDSMAP -- Do condoms work?
CATIE News -- High prevalence of condom use errors and problems -- implications for HIV prevention messaging
Canadian HIV/AIDS Legal Network -- HIV non-disclosure and the criminal law: Implications of recent Supreme Court of Canada decisions for people living with HIV: Questions & Answers
- Lytle CD, Routson LB, Seaborn GB, Dixon LG, Bushar HF, Cyr WH. An in vitro evaluation of condoms as barriers to a small virus. Sex Transm Dis. 1997 Mar;24(3):161-4.
- Sanders SA, Yarber WL, Kaufman EL, Crosby RA, Graham CA, Milhausen RR. Condom use errors and problems: a global view. Sex. Health. 2012 Feb 17;9(1):81-95.
- Lindberg L, Sonenstein F, Ku L, Levine G. Young men's experience with condom breakage. Family Planning Perspectives. 1997 Jun;29(3):128-31.
- Steiner MJ, Taylor D, Hylton-Kong T, Mehta N, Figueroa JP, Bourne D, et al. Decreased condom breakage and slippage rates after counseling men at a sexually transmitted infection clinic in Jamaica. Contraception. 2007 Apr;75(4):289-93.
- Weller S, Davis K. Condom effectiveness in reducing heterosexual HIV transmission. Cochrane Database Syst Rev. 2002;(1):CD003255.
- Vittinghoff E, Douglas J, Judson F, McKirnan D, MacQueen K, Buchbinder SP. Per-contact risk of human immunodeficiency virus transmission between male sexual partners. Am. J. Epidemiol. 1999 Aug 1;150(3):306-11.
- Golden M. HIV serosorting among men who have sex with men: implications for prevention. 13th Conference on Retroviruses and Opportunistic Infections. 2006;Abstract 163.
- Detels R, English P, Visscher BR, Jacobson L, Kingsley LA, Chmiel JS, et al. Seroconversion, sexual activity, and condom use among 2915 HIV seronegative men followed for up to 2 years. J. Acquir. Immune Defic. Syndr. 1989;2(1):77-83.
- Minnis AM, Padian NS. Effectiveness of female controlled barrier methods in preventing sexually transmitted infections and HIV: current evidence and future research directions. Sex Transm Infect. 2005 Jun;81(3):193-200.
- French PP, Latka M, Gollub EL, Rogers C, Hoover DR, Stein ZA. Use-effectiveness of the female versus male condom in preventing sexually transmitted disease in women. Sex Transm Dis. 2003 May;30(5):433-9.
- Kelvin EA, Mantell JE, Candelario N, Hoffman S, Exner TM, Stackhouse W, et al. Off-label use of the female condom for anal intercourse among men in New York City. Am J Public Health. 2011 Dec;101(12):2241-4.
- Cohen MS, Chen YQ, McCauley M, Gamble T, Hosseinipour MC, Kumarasamy N, et al. Prevention of HIV-1 infection with early antiretroviral therapy. N. Engl. J. Med. 2011 Aug 11;365(6):493-505.
- Grant RM, Lama JR, Anderson PL, McMahan V, Liu AY, Vargas L, et al. Preexposure chemoprophylaxis for HIV prevention in men who have sex with men. N. Engl. J. Med. 2010 Dec 30;363(27):2587-99.
- Baeten JM, Donnell D, Ndase P, Mugo NR, Campbell JD, Wangisi J, et al. Antiretroviral prophylaxis for HIV prevention in heterosexual men and women. N. Engl. J. Med. 2012 Aug 2;367(5):399-410.
- Thigpen MC, Kebaabetswe PM, Paxton LA, Smith DK, Rose CE, Segolodi TM, et al. Antiretroviral preexposure prophylaxis for heterosexual HIV transmission in Botswana. N. Engl. J. Med. 2012 Aug 2;367(5):423-34.
- Cardo DM, Culver DH, Ciesielski CA, Srivastava PU, Marcus R, Abiteboul D, et al. A case-control study of HIV seroconversion in health care workers after percutaneous exposure. Centers for Disease Control and Prevention Needlestick Surveillance Group. N. Engl. J. Med. 1997 Nov 20;337(21):1485-90.
- Vallabhaneni S, Li X, Vittinghoff E, Donnell D, Pilcher CD, Buchbinder SP. Seroadaptive Practices: Association with HIV Acquisition among HIV-Negative Men Who Have Sex with Men. PLoS ONE. 2012;7(10):e45718.
- Boily M-C, Baggaley RF, Wang L, Masse B, White RG, Hayes RJ, et al. Heterosexual risk of HIV-1 infection per sexual act: systematic review and meta-analysis of observational studies. Lancet Infect Dis. 2009 Feb;9(2):118-29.
- Holmes KK, Levine R, Weaver M. Effectiveness of condoms in preventing sexually transmitted infections. Bull. World Health Organ. 2004 Jun;82(6):454-61.
- Ward H, Rönn M. Contribution of sexually transmitted infections to the sexual transmission of HIV. Curr Opin HIV AIDS. 2010 Jul;5(4):305-10.
James Wilton is the Coordinator of the Biomedical Science of HIV Prevention Project at CATIE. James is currently completing his master's degree of Public Health in Epidemiology at the University of Toronto and has completed an undergraduate degree in Microbiology and Immunology at the University of British Columbia.