SNS Research Brief 47. Using lotteries to prevent HIV

HIV and Aids are still major health issues

The number of individuals infected by HIV was estimated to 1.4 million in 2015 alone. The situation is most urgent in sub-Saharan Africa, where approximately 26 million people have been infected by the virus. The epidemic is a growing financial problem, especially in Africa. Accordingly, there is a crucial need for efficient HIV prevention.

Lotteries as an incentive to prevent HIV

This report describes the results of the first big scale trial that uses participation in a lottery as a driving force to reduce the spread of the HIV virus. The lottery aimed to influence the expected cost of having unprotected sex, and in turn reduce the risk of the participants being infected or spread the virus further. The study was conducted under a two-year period in Lesotho, a country that has been deeply afflicted by the HIV epidemic.

The study was a parallel group randomised trial, meaning that participants were randomly selected into either one of two treatment groups, or into a control group. The treatment groups were offered to participate in the lottery, where the prize amount differed between the two. Individuals in the treatment groups were then awarded a lottery ticket only if they tested negative for two curable STIs in the week before the lottery draw. The lottery draws were conducted every four months.

What can be learned from the lotteries?

• Individuals that take financial risks are more prone to engage in risky sexual behavior. Participants that were willing to take financial risks were more likely to be HIV positive and less likely to report that they practice safe sex.
• The number of individuals infected by HIV decreased substantially. The lotteries caused risk-seeking individuals to take less risky decisions when it came to their sex life while the behaviour among the group of risk-averse individuals did not change.
• An efficient and cheap intervention. A prevention programme using lotteries is likely to be executed at a lesser cost than traditional financial incentive programmes, as only the winners need to get paid.

The programme is unique by being the first large-scale trial to test lotteries as incentives to HIV prevention, and it turned out to be successful in significantly decreasing HIV incidence among risk-seeking individuals. This implies that the lotteries may be an adequate intervention to reach groups that are at a high risk of contracting HIV.

The report was presented at an IIES/SNS International Policy Talk at SNS in Stockholm on January 23, 2018. Anna Mia Ekström, Professor at Karolinska Institutet, and Åsa Andersson, Senior Programme Specialist at Sida, commented on the report.

Authors

Martina Björkman Nyqvist, Associate Professor at the Department of Economics, Stockholm School of Economics

Jakob Svensson, Professor at the Institute for International Economic Studies, Stockholm University

* This is a summary of a research brief in Swedish “Hivprevention med hjälp av lotterier”.