HIV transmission occurs in three ways: (a) sexual intercourse; (b) exposure to infected blood; or (c) mother to child transmission through birth or breast milk.1 Sexual transmission is the primary transmission mechanism worldwide, and accounts for more than 90% of infections in sub-Saharan Africa.2 Condoms can prevent infection by reducing the likelihood of transmission during sexual intercourse. (More about HIV/AIDS.)
There is strong reason to believe that condoms, when consistently used, reduce the likelihood of transmission. However, there is somewhat weaker evidence regarding whether condom promotion and distribution programs result in increased condom use and consequently, reduced HIV/AIDS transmission.4
Effectiveness of condoms when used consistently: A Cochrane analysis was conducted of 14 studies including 4,709 participants. All participants were part of couples in which one partner was infected with HIV and the other was not. The review compared cohorts of "always" users of condoms to "never" users and estimated that consistent condom use results in an 80% reduction in HIV incidence.5 Because the reviewed studies are not randomized controlled trials, the authors note that other factors may have caused the observed reduction in HIV transmission rates. Factors may have included (a) frequency of sexual activity; (b) the fact that condom users are self-selected, which introduces other, unknown biases; or (c) rates of other risky behaviors, like drug use.6
Effectiveness of condom promotion and distribution programs. The Disease Control Priorities Report lists 11 individual studies on the effects of condom promotion and distribution programs.7 10 of 11 studies found increased condom use and two of three (which measured HIV incidence) found reduced incidence.8 However, (a) many of these studies were not randomized controlled trials; (b) they often ran programs (e.g., one-on-one counseling about sexual behavior for study subjects every 3 months, as in Bentley 1998) that are not necessarily representative of programs implemented by NGOs more broadly; (c) many rely on self-reported condom use information; (d) many are focused on highly specific groups of people (such as sex workers, featured in 5 of the 11 studies listed by the DCP) or means of provision (such as provision directly in motel rooms, as in Egger 2000).
Condom promotion and distribution has been credited with large-scale, successful programs in the developing world to control HIV/AIDS. Below we summarize reports on Thailand (Levine 2007) and Uganda (World Health Organization 2000).
It is possible that increased condom promotion and distribution could lead to increased sex frequency and an increase in high-risk sexual activities. The Disease Control Priorities in Developing Countries report raises this concern and states that available data suggest that "sex education, including condom promotion, does not encourage or increase sexual activity (Kirby 2001)."14
We have not done thorough cost-effectiveness analysis of this program. Because such analysis is highly time-consuming - and because the results can vary significantly depending on details of the context - we generally do not provide cost-effectiveness analysis for an intervention unless we find what we consider to be a strong associated giving opportunity.
We provide some preliminary figures based on the Disease Control Priorities in Developing Countries report, which we previously used for cost-effectiveness estimates until we vetted its work in 2011, finding major errors that raised general concerns.
The Disease Control Priorities in Developing Countries report estimates costs at $52-$112 per disability-adjusted life-year (DALY) averted for this program type.15 This is reasonably strong cost-effectiveness.16 (More on the DALY metric)
Using a simple conversion calculation,17 we estimate that $52-$112 per DALY averted is equivalent to $1,020-$2,240 per HIV infection averted.
These estimates should be used even more cautiously than most cost-effectiveness estimates given the uncertainty about the impact of these programs, noted above.
"HIV transmission predominantly occurs through three mechanisms: sexual transmission, exposure to infected blood or blood products, or perinatal transmission (including breastfeeding)." Jamison et al. 2006, Pg 333.
"Worldwide, sexual intercourse is the predominant mode of transmission, accounting for approximately 80 percent of infections (Askew and Berer 2003). Sexual intercourse accounts for more than 90 percent of infections in Sub-Saharan Africa." Jamison et al. 2006, Pg 334.
"Targeted distribution and placement of condoms in locations such as bars or brothels; distribution linked to voluntary counseling and testing and sexually transmitted infection care to ensure universal access; information, education, and communication, including education through literature, classroom, and clinical settings and radio, newspapers, and television." Jamison et al. 2006, Pg 74, Table 2.B.2.
"Given the central role that condom promotion, distribution, and social marketing has played in HIV prevention programs, the lack of data on the relative cost-effectiveness of such programs 20 years into their implementation is striking. It is beyond dispute that the use of a condom by sexual partners who are HIV-discordant is extraordinarily cost-effective, given the low cost and high effectiveness of the condom in preventing HIV transmission. Information on the relative costs and effectiveness of different approaches to increasing condom use by serodiscordant sexual partners is not available,with the shortage of information being far more acute for effectiveness than for costs. In the absence of empirical evidence, decision makers are reduced to formulating policy on the basis of theory and common sense." Jamison et al. 2006, Pg 345.
"Cohort studies of sexually active HIV serodiscordant couples with follow-up of the seronegative partner, provide a situation in which a seronegative partner has known exposure to the disease and disease incidence can be estimated. When some individuals use condoms and some do not, namely some individuals use condoms 100% of the time and some never use (0%) condoms, condom effectiveness can be estimated by comparing the two incidence rates. Condom effectiveness is the proportionate reduction in disease due to the use of condoms ... For inclusion, studies had to have: (1) data concerning sexually active HIV serodiscordant heterosexual couples, (2) a longitudinal study design, (3) HIV status determined by serology, and (4) contain condom usage information on a cohort of always (100%) or never (0%) condom users ... This review indicates that consistent use of condoms results in 80% reduction in HIV incidence." Weller and Davis-Beaty 2002, abstract.
"The lack of random assignment of individuals to use or not use condoms can result in an unequal distribution of HIV risk factors across those categories and can bias estimates of condom effectiveness. Factors associated with both seroconversion and condom use can bias estimates of condom effectiveness. Differences between "always" and "never" users in duration and frequency of exposure or in infectivity and susceptibility can bias estimates. Because condom use is associated with HIV risk factors, the association between condom use and seroconversion is biased by the self-selection of individuals into the always and never condom usage groups. Notably, condom non-users in recent studies may be more likely to be IDUs (Padian 1997) and may be more likely to engage in other risky behaviors (Skurnick 1998; Kennedy 1993; Pinkerton 1995; Ross 1988). Higher HIV transmission among partners of IDUs (Padian 1997) and a preponderance of partners of IDUindex cases among condom non-users, can inflate incidence estimates for condom nonusers and result in an overestimation of condom effectiveness." Weller and Davis-Beaty 2002, Pg 3.
Jamison et al. 2006, Pgs 337-8.
Jamison et al. 2006, Pgs 337-8.
"In 1991, the national AIDS committee led by Thailand's prime minister implemented the '100 percent condom program,' in which all sex workers in sex establishments were required
to use condoms with clients." Levine 2007, Pg 1.
"Health officials provided boxes of condoms free of charge, and local police held meetings with sex establishment owners and sex workers, despite the illegality of prostitution. Men seeking treatment for sexually transmitted infections (STIs) were asked to name the sex establishment they had used, and health officials would then visit the establishment to provide more information." Levine 2007, Pg 1.
"Condom use in sex establishments nationwide increased from 14 percent in early 1989 to more than 90 percent by June 1992 ... According to estimates by the Thai Working Group on HIV/AIDS Projection for the Ministry of Public Health, the number of new HIV cases decreased by more than 80 percent from 1991 to 2001." Levine 2007, Pg 3 (also see chart).
"Since 1993, HIV infection rates among pregnant women, a key indicator of the progress of the epidemic, have been more than halved in some areas and infection rates among men seeking treatment for sexually transmitted infections have dropped by over a third... In the capital city Kampala, the level of HIV infection among pregnant women attending antenatal clinics fell from 31% in 1993 to 14% by 1998. Meanwhile, outside Kampala, infection rates among pregnant women under 20 dropped from 21% in 1990 to 8% in 1998. Elsewhere, among men attending STI clinics, HIV infection rates fell from 46% in 1992 to 30% in 1998." World Health Organization 2000, Pg 20.
World Health Organization 2000, Pgs 22-23.
Jamison et al. 2006, Pg 344.
Jamison et al. 2006, Pg 74.
See Jamison et al. 2006, Pgs 41-42, for a chart of the cost-effectiveness range (measured in cost per DALY) for many programs.
20 DALYs per infection averted: "The estimates of cost per disability-adjusted life year (DALY) saved assume a uniform 20 DALYs lost per infected adult (Murray and Lopez 1996) and 25 DALYs lost per infected child (Marseille and others 1999) and do not account for the increasing proportion of people living with HIV/AIDS in developing countries who will have access to antiretroviral therapy over the coming years." Jamison et al. 2006, Pg 344. Note that we assume all prevented HIV infections are among adults (a relevant study states, "Here we present and compare the results of two alternative methods of obtaining incidence estimates: the first based on detuned ELISA assays, the second using a modelling approach to the analysis of age-specific prevalence data ... The two methods give results that are in close agreement and of comparable precision. The annual incidence increases from close to 0 at age 15 years to 27% among 20-24 year old women and declines with age thereafter." Williams et al. 2000, abstract.)