Lottery Ticket Approach Leads to Drastic Reduction in HIV Prevalence

Researchers funded by the World Bank arrived at a wildly unorthodox and unexpectedly effective strategy for preventing HIV in the African nation of Lesotho: A lottery program that offered participants an opportunity to win cash on the condition that they tested negative for sexually transmitted infections.

The lotteries led to a 21.4 percent reduction in HIV incidence among participants over a two-year period, and a reduction of more than 60 percent among participants identified as “risk-loving individuals” — those who were identified at the study’s start as people who enjoyed risky behavior.

“We are the first to find a significant reduction in HIV incidence though behavioral intervention,” Professor Martina Björkman Nyqvist of the Stockholm School of Economics, a lead researcher on the project, told Foreign Policy.

In Lesotho — a small, mountainous country of 2.1 million that is completely surrounded by South Africa — some 43 percent of the population lives on less than $1.25 a day and 23 percent of adults are infected with HIV. Among young people the rate is even higher, with 41 percent of people between the ages of 30 and 34 infected.

Researchers worked with 3,029 volunteers in 29 villages across the country to see whether the opportunity to enter a lottery in exchange for a clean test result might lower these infection rates. Participants testing negative for curable sexually transmitted infections were entered automatically to win cash prizes of either $50 or $100. While the study focused on HIV, the lottery was tied to other STIs, so that HIV-positive individuals, for whom safe behavior is paramount, could also participate. All participants, including members of the control group, received in-kind rewards for participation.

The lotteries were most successful among risk seekers, identified through “the perceived value of a risky gamble.” “As risky sexual behavior, which is responsible for the vast majority of new HIV infections, also involves a risky gamble, lottery programs may better target those at higher risk of getting infected by HIV,” the authors wrote in a World Bank working paper published in March.

In a country with a low life expectancy, the consequences of sexual risk-taking can seem distant and the rewards immediate, Nyqvist said. The lotteries were designed to rebalance that psychological equation.

“Broadly, it has been popular in the past decade or so within international development to look at conditional cash transfer programs, and these have been found to have big effects when it comes to school attendance, health checkups, these kind of things,” Nyqvist said, referring to programs that offer small payments in reward for compliance with a set of criteria. The Lesotho program takes that line of thinking and adds a twist: Higher risk, higher reward.

“The perceived return from participating in a lottery may also be higher than the return from an incentive program that pays the expected return with certainty,” Nyqvist and her co-authors wrote.

But the researchers sounded a note of caution about applying these findings to other countries. “The results are really big, amazingly big,” Nyqvist said. “But the results apply to Lesotho. To conclude that this has external validity, we would need to replicate the lotteries elsewhere.” One condition she identified as specific to the region was the unusually high levels of infection.

The conventional wisdom on HIV/AIDS prevention argues that fighting the spread of the infection requires making condoms more widely available, improving accessibility to antiretroviral drug regimes, and educating the public about the virus and how it is transmitted. These latest findings do not necessarily dispute that thinking, but point to a new, simple, and cheap approach.

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