Hearing about the recent successful microbicide clinical trial (CAPRISA 004) which, after years of not-so-great-results with other microbicides, is exciting enough, but now there is more good news on the HIV prevention front in low- and middle-income countries.

A World Bank - sponsored program in Malawi that gives small monthly payments to girls and young women (13-22) and their families with the goal of reducing girls' risky sexual encounters. There is a description of the study on the World Bank website that details the program, the forces that seem to be at work,  and its unexpected findings.

Here's a synopsis:

The money (as much as $15/month) is given to young girls and their families if the girls stayed in school. A control group received no cash reward for schooling. Another group of girls received the cash without any schooling strings attached  A year later, they found that those girls who received cash rewards for attending school were more likely to still be enrolled in school than the control group who received no cash.

Here's where it gets good!

They also found that those girls who received the cash (after 18 months in the study) were 60% less likely to be infected with HIV (and genital herpes). This finding also held for the girls in the group that received the money (without school strings attached).

Why?

From the World Bank website:

How did it happen? The key seems to be an "income effect" on the sexual behaviors of young women receiving cash payments. A year after the program started, girls who received payments not only had less sex, but when they did, they tended to choose safer partners, says Berk Özler, a senior economist at the Development Research Group who conducted the study with Sarah Baird of George Washington University and Craig McIntosh at the University of California, San Diego. In fact, the infection rate among those partners is estimated to be half of that of partners of the control group.
The cash transfers may have led to a drop in the so-called "transactional sex." At the beginning of the study, a quarter of sexually-active participants said they started relationships because they "needed his assistance" or "wanted gifts/money." Meanwhile, among the sexually-active schoolgirls in the control group, 90% said they received an average of US$6.50 a month in gifts or cash from their partners. Such "gifts" are significant, given the country's GDP per capita was $287.5 in 2008.
After a year, schoolgirls receiving payments from the cash-transfer program seemed to avoid older men, who tend to be wealthier and are much more likely to be HIV positive than schoolboys. The sexual partners were two years older on average than the girls, compared with three years for the control group.

Conditional cash transfer (CCT) programs that provide regular payments to poor families if their children stay in school (or get vaccinations, or engage in other desirable behaviors) have become a favoured anti-poverty intervention in low- and middle-income countries, and a new Economist report on CCTs gives a concise explanation for the reason:

The programmes have spread because they work. They cut poverty. They improve income distribution. And they do so cheaply.

The Malawi study suggests that, at least in the case of behaviors related to HIV, payments may not even need to be conditional if the money reduces pressures that lead to unhealthy behaviors. (Girls' choice of sexual partners may or may not be based on HIV considerations, but they apparently prefer sexual partners closer to their own ages, who are less likely to be HIV positive.)

Both the microbicidal gel (CAPRISA004) and cash-payment interventions have an important aspect in common: they put decisions about safer sex in women's hands. It's important that the gel, unlike condoms, can be used by women without men's consent or knowledge - study participants were instructed to use pre-filled gel applicators within 12 hours before sex and as soon as possible within 12 hours following it.
Halting the spread of HIV will require a combination of interventions, both existing and new.

These studies suggest that many women in low- and middle-income countries want to have sex that is safer. We need to make options for safer sex more readily available to them.