Comportements sexuels risques et incitations : l'impact des nouveaux traitements sur la prevention du VIH

This article studies the interaction between two individual decisions in the context of sexually transmitted diseases: on the one hand, the choice the of risk level, on the other hand, the decision to get tested. Our angle here is economic epidemiology, which aims at identifying the essential arbitrages that involve private decisions. Since testing opens access to treatments for a disease, it reduces the private cost of risk taking, all the more so when available treatments are more efficacious. From this, it stems that improvements in treatmentds can spur an increase in the risk level, by diminishing the cost associated with risk for those individuals who have opted for testing. An empirical analysis based on data from the San Francisco Stop Aids Project confirms this theoretical prediction. The apparition, during the year 1996, of new treatments against HIV coincided with an increaese in risky behavior within the tested population (test group) but not within the population that had not undertaken testing (control group).