Subsidizing Safe Sex By Paying For Negative STD Tests

It turns out, if the doctor gives you money when you get a clean bill of health, you work harder to be healthy.

Subsidizing Safe Sex By Paying For Negative STD Tests

The threat of disease or death isn’t convincing enough to stop the spread of HIV and other sexually transmitted infections (STI). Perhaps cash will prove more persuasive.


Scientists at MIT’s Poverty Lab recently published findings in BMJ Open that tested that theory in Tanzania. They used payments known as conditional cash transfers (CCTs)–known to encourage socially desirable behavior elsewhere in areas like such as school enrollment and medical check-ups–to deter risky sex among young people (18 to 30-year-olds) in Tanzania.

As much as 5% of Tanzania’s population is infected with HIV/AIDS. Although rates have declined there during the last five years, the country’s sub-Saharan neighbors are not so lucky. Just 10 sub-Saharan countries account for more than one-third of people infected with HIV worldwide; an equal proportion of new cases also occur there. It’s clear controlling existing infections is not enough; cheap and effective prevention is needed.

The MIT researchers asked about 2,000 participants to receive tests for four common STIs–chlamydia, gonorrhea, trichomonas, and M. genitalium–every four months during the course of a year. If results were negative, participants were paid $10, $20, or nothing depending on the experimental group. If positive, participants were treated, but did not receive cash. The STIs served as a proxy for HIV infection risk from sex, since payments were not contingent on HIV status, given the stigma attached to the infection in many communities.

At first, there was no effect. STI rates among those receiving cash were the same as those who did not. But by the end of the year, the numbers looked very different. The high cash payment ($20) group reduced the number of STI infections by 19%, while the number of those with STI rose both in the control group (by 13%) and the one receiving only $10 (by 19%).

While the effect was clear–more money equals fewer STIs–those effects did not show up until much later and $10 proved ineffective at reducing STI infections. The researchers could offer no easy answers, but speculate that behavior change may simply take time to occur, and prices are clearly important.

New research (PDF) may shed some light on that questions. One of the lead researchers, Jonathan Robinson, now an assistant professor of economics at the University of California, Santa Cruz, is studying how incentives affect adoption preventative health measures in developing countries.


Returning to Africa, Robinson distributed coupons to Kenyan families that could be redeemed for shoes that prevented parasitical infections. One of the main conclusions? Price matters more than anything else. But the cost, even a few dollars per person, can be very low.

A good bargain all around.

About the author

Michael is a science journalist and co-founder of Publet: a platform to build digital publications that work on every device with analytics that drive the bottom line. He writes for FastCompany, The Economist, Foreign Policy and others on science, economics, and the environment.