By Priya Shetty of Nature magazine

South African teenagers could pocket as much as 2,700 rand (US$400) over the next 18 months in exchange for staying HIV-free. South Africa has 17% of the world's HIV-infected people, with young girls one of the highest risk groups, because poverty drives them to have sex in exchange for gifts. Researchers now want to see whether using cash payments as a reward for getting good grades and having annual HIV tests could curb the girls' risky sexual behavior.

Last September, the Centre for the AIDS Programme of Research in South Africa (CAPRISA) in Durban enrolled male and female students at 14 schools in a rural district in KwaZulu-Natal in a trial to test the cash incentive scheme. Students aged 13 years and older at seven schools were offered the payments, and students at the other seven schools were used as controls.

A similar study of Malawian schoolgirls who were offered cash to stay in school found that the HIV infection rate was 60% lower than those not receiving the money, causing a flurry of excitement at the 2010 International AIDS conference in Vienna. But that trial measured HIV rates only as an afterthought, so the team couldn't reliably say whether the two study groups started with similar infection rates, says Quarraisha Abdool Karim, lead researcher on the CAPRISA trial, which is named RHIVA (Reducing HIV in Adolescents).

Test drive

South Africa is currently undertaking a mammoth drive to test 15 million people for HIV by the end of this month; 12 million have been tested so far. The country's health minister, Aaron Motsoaledi, is keen to test schoolchildren too, which has stirred controversy among human-rights groups and parents, who argue that teenagers may not be emotionally equipped to deal with an HIV-positive diagnosis. But Abdool Karim doesn't see any other option. In 14-year-old South African girls, HIV prevalence is about 2% and there is a steady rise with age -- by age 20, as many as 16% could be infected.

The CAPRISA trial, which is due to run until the end of 2012, differs from most HIV-prevention programs by trying to influence male behavior as well. Too many target only women, says Sarah Hawkes, a sexual-health expert at University College London. She notes: "Men are driving the epidemic -- through their sexual behaviors, drug-taking, risk-taking and the fact that they often hold the balance of power in decision-making in intimate relationships." It is hoped that the boys involved in this project will be less likely to engage in risky behaviors in the future.

Many health experts are enthusiastic about the use of cash incentives--whereas educating people about health risks may not always change behavior, paying them might. For instance, India's cash scheme to encourage women to give birth in medical facilities has produced good results. Financial incentives have also led to higher rates of smoking cessation in the United States.

Cash controversy

Yet the idea has its detractors. "Development practitioners and governments across the world need to question where incentivizing behavior change through money will end," says Sophie Harman, an HIV/AIDS policy expert at City University, London.

Elizabeth Pisani, an AIDS epidemiologist, formerly with the UN program on HIV/AIDS (UNAIDS), is concerned that such schemes are well intentioned but unrealistic. "Girls in South Africa have sex for the same reason that girls elsewhere have sex: because they fancy the bloke, because sex is fun, because it makes them feel grown-up, or loved, or desirable, or cool. Will cash make a girl have safer sex, use condoms more frequently? If so, there's every chance that the condoms will disappear once the bribes do."

Jerome Singh, an ethicist on the CAPRISA trial and ethics director for the Grand Challenges in Global Health initiative, funded by the Bill & Melinda Gates Foundation, points out that the students aren't just handed the cash. "Study participants are taught life-orientation skills, including how to manage their personal finances."

The urgency of the AIDS epidemic warrants trying whatever might work, says Abdool Karim. "We have to think out of the box. Young women are infected before they even have a glimpse of what their life could be like," she says.

This article is reproduced with permission from the magazine Nature. The article was first published on June 6, 2011.