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Risky Business: The Market for Unprotected Commercial Sex

Development Challenge

The HIV epidemic continues to be a public health issue - nearly 20,000 people become infected with HIV every day. A large proportion of these new cases are among sex workers who have unprotected sex with clients. Infection rates among sex workers are very high, and this is especially true in developing countries with concentrated HIV epidemics. Condoms are an effective defense against the transmission of sexually transmitted infections (STIs).  But despite substantial efforts to educate sex workers about  using condoms to prevent the risk of STIs, and particularly the risk of HIV infection, large numbers of sex workers are still not using condoms with clients.

Much of the health policy literature makes two primary arguments: In many cases, sex workers engage in unprotected sex because they are uninformed of the risks; or in the cases in which sex workers are aware of the risk, the hypothesis is that non–condom use occurs because condoms are either very expensive or unavailable. This study offers another possible explanation: sex workers are willing to risk HIV infection by having unprotected sex with clients if they are adequately compensated for such a risk.


In contrast to countries that have a generalized HIV epidemic (defined by UNAIDS as an HIV prevalence rate greater than 1% of the general population), the HIV epidemic in Mexico is concentrated in groups with high-risk behavior, such as sex workers.  The Mexican government has conducted a large-scale education campaign to promote condom use and to increase awareness about the risks of unprotected sex, which has led to fairly high condom use among sex workers.  Additionally, many Mexican states regulate the sex work industry, which has led to increased transparency about clients of sex workers.

Research for the study was conducted in two Mexican states: Morelos and Michoacan. Morelos has one of the highest rates of reported HIV in the country. Michoacan is closer to the median rate for Mexico’s national infection rate. The states were selected on the basis of HIV prevalence, previous experience with behavioral studies, and willingness of the local HIV advocacy groups to collaborate.

Evaluation Strategy

The study’s empirical objectives were to obtain consistent estimates of the price differential between condom and non–condom use, and to understand how this differential varies due to client and sex worker preferences. To do so, researchers first mapped the universe of sex workers to develop a sample frame and number of interview participants.  Key informants (e.g., taxi drivers, police, and NGO workers) helped researchers identify potential gathering sites for commercial sex workers. After mapping these locations, researchers estimated the population size at each site to construct a representative sample.  

A panel data set was created from in-depth interviews and focus groups that were conducted with sex workers and their clients on the prior three to four transactions. The survey included sex worker demographics and characteristics, as well as retrospective details – including the cost of the service and whether a condom was used – of the last three transactions in Morelos and the last four transactions per sex worker in Michoacan, for a total of 3,837 observations. Given that most sex workers had more than three transactions per week, and the retrospective data was less than a week old, recall bias was not viewed as a significant issue.

In the survey, sex workers were asked to recall if a condom was used in these transactions, and if so, who suggested the use. Responses to these questions indicated the level of risk behavior exhibited by the sex worker (e.g., if the sex worker suggested condom use, it was interpreted as a signal that she is more risk averse than the client).  Researchers then constructed price payoffs for both sex workers and clients as well as a bargaining model of commercial sex, with weights assigned depending on the sex worker’s and the clients’ relative bargaining power.

Results and Policy Implications

The results of the analysis were consistent with the researchers’ bargaining model; that is, sex workers are willing to assume the risks associated with providing unprotected sex to clients who request not using a condom. Overall, the average price per act was 447 Mexican pesos (about U.S. $45).  When the clients’ suggested not using a condom, the price differential was 23 percent higher. This premium increased to 46 percent if the sex worker was considered very attractive, a likely indication of her bargaining power.

Results indicate that the sex workers were the ones to negotiate condom use in the vast majority of transactions, whereas clients suggested condom use only in 152 of the 3,485 transactions that used condoms. Of the transactions that did not use condoms at all, results indicate that 66 percent of these transactions were because a client suggested not using a condom. However, if a sex worker suggested not using a condom, clients were given a 20 percent discount. This discount reflects the sex workers’ preferences for greater risk over the clients preferred non–condom use.

  Condom Used Condom Not Used
Sex worker suggested condom use Client's WTP not to use a condom < minimum compensation to sex worker to take the risk = Default case Client's WTP to use a condom > minimum compensation to sex worker to take the risk = Price higher than default case
Client suggested condom use Sex worker's WTP not to use a condom > minimum compensation to sex worker to take the risk = Price lower than default case Client's WTP for not using a condom > minimum compensation to pay the sex worker to take the risk = Price higher than default case

The findings from the study suggest that the most effective interventions for reducing HIV and STI transmission through commercial sex will be those that target both the supply side (the sex workers and their agents) and the demand side (the clients) of the market for commercial sex. While continued efforts to educate sex workers about the risks of unprotected sex are recommended, interventions to empower sex workers and to improve their negotiating skills can also serve to increase their bargaining power so that they are able to capture more of their clients’ willingness to pay and increase their incomes. On the demand side, efforts to increase clients’ preference for condom use would involve education on the risks of unsafe sex or marketing the “joy of safe sex to them”. However, while demand side interventions are as important, if not more important than supply side interventions, they are also likely to be considerably more expensive due to the number of clients and the difficulty in identifying and targeting clients of sex workers.



Photo credit: Anuska Sampedro/Flickr